This is intended to fix a test failure that occurs in the p2p state provider. The issue presents as the state provider timing out waiting for the consensus params response. 

The reason that this can occur is because the statesync reactor has the possibility of attempting to respond to the params request before the state provider is ready to read it. This results in the reactor hitting the `default` case seen here and then never sending on the channel. The stateprovider will then block waiting for a response and never receive one because the reactor opted not to send it.

When statesync is stopped during shutdown, it has the possibility of deadlocking. A dump of goroutines reveals that this is related to the peerUpdates channel not returning anything on its `Done()` channel when `OnStop` is called. As this is occuring, `processPeerUpdate` is attempting to acquire the reactor lock. It appears that this lock can never be acquired. I looked for the places where the lock may remain locked accidentally and cleaned them up in hopes to eradicate the issue. Dumps of the relevant goroutines may be found below. Note that the line numbers below are relative to the code in the `v0.35.0-rc1` tag.

```
goroutine 36 [chan receive]:
github.com/tendermint/tendermint/internal/statesync.(*Reactor).OnStop(0xc00058f200)
        github.com/tendermint/tendermint/internal/statesync/reactor.go:243 +0x117
github.com/tendermint/tendermint/libs/service.(*BaseService).Stop(0xc00058f200, 0x0, 0x0)
        github.com/tendermint/tendermint/libs/service/service.go:171 +0x323
github.com/tendermint/tendermint/node.(*nodeImpl).OnStop(0xc0001ea240)
        github.com/tendermint/tendermint/node/node.go:769 +0x132
github.com/tendermint/tendermint/libs/service.(*BaseService).Stop(0xc0001ea240, 0x0, 0x0)
        github.com/tendermint/tendermint/libs/service/service.go:171 +0x323
github.com/tendermint/tendermint/cmd/tendermint/commands.NewRunNodeCmd.func1.1()
        github.com/tendermint/tendermint/cmd/tendermint/commands/run_node.go:143 +0x62
github.com/tendermint/tendermint/libs/os.TrapSignal.func1(0xc000629500, 0x7fdb52f96358, 0xc0002b5030, 0xc00000daa0)
        github.com/tendermint/tendermint/libs/os/os.go:26 +0x102
created by github.com/tendermint/tendermint/libs/os.TrapSignal
        github.com/tendermint/tendermint/libs/os/os.go:22 +0xe6

goroutine 188 [semacquire]:
sync.runtime_SemacquireMutex(0xc00026b1cc, 0x0, 0x1)
        runtime/sema.go:71 +0x47
sync.(*Mutex).lockSlow(0xc00026b1c8)
        sync/mutex.go:138 +0x105
sync.(*Mutex).Lock(...)
        sync/mutex.go:81
sync.(*RWMutex).Lock(0xc00026b1c8)
        sync/rwmutex.go:111 +0x90
github.com/tendermint/tendermint/internal/statesync.(*Reactor).processPeerUpdate(0xc00026b080, 0xc000650008, 0x28, 0x124de90, 0x4)
        github.com/tendermint/tendermint/internal/statesync/reactor.go:849 +0x1a5
github.com/tendermint/tendermint/internal/statesync.(*Reactor).processPeerUpdates(0xc00026b080)
        github.com/tendermint/tendermint/internal/statesync/reactor.go:883 +0xab
created by github.com/tendermint/tendermint/internal/statesync.(*Reactor.OnStart
        github.com/tendermint/tendermint/internal/statesync/reactor.go:219 +0xcd)
```

This test reliably gets hung up on network configuration, (which may
be a real issue,) but it's network setup is handcranked and we should
ensure that the test focuses on it's core assertions and doesn't fail for 
test architecture reasons.

I've been noticing that there are a number of situations where the
statesync reactor blocks waiting for peers (or similar,) I've moved
things around to improve outcomes in local tests.

* Revert "statesync: keep peer despite lightblock query fail (#6692)"

This reverts commit 50b00dff71.

When a peer responds with no lightblock for the height we queried, we call the [removePeer method](https://github.com/tendermint/tendermint/blob/master/internal/statesync/reactor.go#L339). This removes the peer from the [dispatcher's list of called peer's](ad65883152/internal/statesync/dispatcher.go (L159)). When the dispatcher then receives responses from the removed peer, it [drops their responses](ad65883152/internal/statesync/dispatcher.go (L130)). These responses may be meaningful or contain a block or data that will help statesync proceed.

[The logs](https://gist.github.com/tychoish/34a1f61eaae3c36c23efc7d0001e805c), when this change is applied, show an additional 3 networking testnets passing. 

addresses:  #6691

Having smaller buffers in each reactor/channel will mean that there will be fewer stale messages.

This PR make some tweaks to backfill after running e2e tests:
- Separates sync and backfill as two distinct processes that the node calls. The reason is because if sync fails then the node should fail but if backfill fails it is still possible to proceed.
- Removes peers who don't have the block at a height from the local peer list. As the process goes backwards if a node doesn't have a block at a height they're likely pruning blocks and thus they won't have any prior ones either. 
- Sleep when we've run out of peers, then try again.

## Description

Internalize some libs. This reduces the amount ot public API tendermint is supporting. The moved libraries are mainly ones that are used within Tendermint-core.

I believe that this, in my testing seems to help the e2e state-sync
tests complete more reliably, by fixing some potential, range-related
slice building, as well as the way the test app hashes snapshots.

Additionally, and I'm not sure if we want to do this, but I added this
hook to the reactor that re-sends the request for snapshots during the
retry. This helps in tests prevent systems from getting stuck, but I
think in reality, it might create more traffic, and operators would
just restart a state-syncing node to get a similar effect.

This cleans up the `Router` code and adds a bunch of tests. These sorts of systems are a real pain to test, since they have a bunch of asynchronous goroutines living their own lives, so the test coverage is decent but not fantastic. Luckily we've been able to move all of the complex peer management and transport logic outside of the router, as synchronous components that are much easier to test, so the core router logic is fairly small and simple.

This also provides some initial test tooling in `p2p/p2ptest` that automatically sets up in-memory networks and channels for use in integration tests. It also includes channel-oriented test asserters in `p2p/p2ptest/require.go`, but these have primarily been written for router testing and should probably be adapted or extended for reactor testing.

This tightens up the `PeerManager` and related code, adds a ton of tests, and fixes a bunch of inconsistencies and bugs.

blockchain/vX reactor priority was decreased because during the normal operation
(i.e. when the node is not fast syncing) blockchain priority can't be
the same as consensus reactor priority. Otherwise, it's theoretically possible to
slow down consensus by constantly requesting blocks from the node.

NOTE: ideally blockchain/vX reactor priority would be dynamic. e.g. when
the node is fast syncing, the priority is 10 (max), but when it's done
fast syncing - the priority gets decreased to 5 (only to serve blocks
for other nodes). But it's not possible now, therefore I decided to
focus on the normal operation (priority = 5).

evidence and consensus critical messages are more important than
the mempool ones, hence priorities are bumped by 1 (from 5 to 6).

statesync reactor priority was changed from 1 to 5 to be the same as
blockchain/vX priority.

Refs https://github.com/tendermint/tendermint/issues/5816

After a reactor has failed to parse an incoming message, it shouldn't output the "bad" data into the logs, as that data is unfiltered and could have anything in it. (We also don't think this information is helpful to have in the logs anyways.)

`abci.Client`:

- Sync and Async methods now accept a context for cancellation
    * grpc client uses context to cancel both Sync and Async requests
    * local client ignores context parameter
    * socket client uses context to cancel Sync requests and to drop Async requests before sending them if context was cancelled prior to that

- Async methods return an error
    * socket client returns an error immediately if queue is full for Async requests
    * local client always returns nil error
    * grpc client returns an error if context was cancelled before we got response or the receiving queue had a space for response (do not confuse with the sending queue from the socket client)

- specify clients semantics in [doc.go](https://raw.githubusercontent.com/tendermint/tendermint/27112fffa62276bc016d56741f686f0f77931748/abci/client/doc.go)

`mempool.TxInfo`

- add optional `Context` to `TxInfo`, which can be used to cancel `CheckTx` request

Closes #5190

Refs #2888

Reduces the state sync discovery time from 20 to 15 seconds, and makes it configurable.

On startup, the peer-to-peer stack may have peers connected before the state sync process begins, causing these to not trigger `AddPeer` events and thus not be used for snapshot discovery. Broadcasting a snapshot request to these explicitly makes sure we discover snapshots from existing peers as well.

## Description

This PR wraps the stdlib sync.(RW)Mutex & godeadlock.(RW)Mutex. This enables using go-deadlock via a build flag instead of using sed to replace sync with godeadlock in all files

Closes: #3242

## Description



Closes: #XXX

Fixes #828. Adds state sync, as outlined in [ADR-053](https://github.com/tendermint/tendermint/blob/master/docs/architecture/adr-053-state-sync-prototype.md). See related PRs in Cosmos SDK (https://github.com/cosmos/cosmos-sdk/pull/5803) and Gaia (https://github.com/cosmos/gaia/pull/327).

This is split out of the previous PR #4645, and branched off of the ABCI interface in #4704. 

* Adds a new P2P reactor which exchanges snapshots with peers, and bootstraps an empty local node from remote snapshots when requested.

* Adds a new configuration section `[statesync]` that enables state sync and configures the light client. Also enables `statesync:info` logging by default.

* Integrates state sync into node startup. Does not support the v2 blockchain reactor, since it needs some reorganization to defer startup.