This is, perhaps, the trival final piece of #7075 that I've been
working on.

There's more work to be done: 
- push more of the setup into the pacakges themselves
- move channel-based sending/filtering out of the 
- simplify the buffering throuhgout the p2p stack.

A fourth #7075 component patch to simplify the channel creation interface

Remove v0 blocksync folder structure.

This PR adds an initial set of metrics for use ABCI. The initial metrics enable the calculation of timing histograms and call counts for each of the ABCI methods. The metrics are also labeled as either 'sync' or 'async' to determine if the method call was performed using ABCI's `*Async` methods.

An example of these metrics is included here for reference:
```
tendermint_abci_connection_method_timing_bucket{chain_id="ci",method="commit",type="sync",le="0.0001"} 0
tendermint_abci_connection_method_timing_bucket{chain_id="ci",method="commit",type="sync",le="0.0004"} 5
tendermint_abci_connection_method_timing_bucket{chain_id="ci",method="commit",type="sync",le="0.002"} 12
tendermint_abci_connection_method_timing_bucket{chain_id="ci",method="commit",type="sync",le="0.009"} 13
tendermint_abci_connection_method_timing_bucket{chain_id="ci",method="commit",type="sync",le="0.02"} 13
tendermint_abci_connection_method_timing_bucket{chain_id="ci",method="commit",type="sync",le="0.1"} 13
tendermint_abci_connection_method_timing_bucket{chain_id="ci",method="commit",type="sync",le="0.65"} 13
tendermint_abci_connection_method_timing_bucket{chain_id="ci",method="commit",type="sync",le="2"} 13
tendermint_abci_connection_method_timing_bucket{chain_id="ci",method="commit",type="sync",le="6"} 13
tendermint_abci_connection_method_timing_bucket{chain_id="ci",method="commit",type="sync",le="25"} 13
tendermint_abci_connection_method_timing_bucket{chain_id="ci",method="commit",type="sync",le="+Inf"} 13
tendermint_abci_connection_method_timing_sum{chain_id="ci",method="commit",type="sync"} 0.007802058000000001
tendermint_abci_connection_method_timing_count{chain_id="ci",method="commit",type="sync"} 13
```

These metrics can easily be graphed using prometheus's `histogram_quantile(...)` method to pick out a particular quantile to graph or examine. I chose buckets that were somewhat of an estimate of expected range of times for ABCI operations. They start at .0001 seconds and range to 25 seconds. The hope is that this range captures enough possible times to be useful for us and operators.

This is mostly just reading through the output of uparam, after
noticing that there were a few places where we were ignoring some arguments.

This is another batch of things to cleanup in the legacy P2P system.

A few notes:

- this is not all the deletion that we can do, but this is the most
  "simple" case: it leaves in shims, and there's some trivial
  additional cleanup to the transport that can happen but that
  requires writing more code, and I wanted this to be easy to review
  above all else.
  
- This should land *after* we cut the branch for 0.35, but I'm
  anticipating that to happen soon, and I wanted to run this through
  CI.

This commit should be one of the first to land as part of the v0.36
cycle *after* cutting the 0.35 branch. 

The blocksync/v2 reactor was originally implemented as an experiement
to produce an implementation of the blockstack protocol that would be
easier to test and validate, but it was never appropriately
operationalized and this implementation was never fully debugged. When
the p2p layer was refactored as part of the 0.35 cycle, the v2
implementation was not refactored and it was left in the codebase but
not removed. This commit just removes all references to it.

The code in the Tendermint repository makes heavy use of import aliasing.
This is made necessary by our extensive reuse of common base package names, and
by repetition of similar names across different subdirectories.

Unfortunately we have not been very consistent about which packages we alias in
various circumstances, and the aliases we use vary. In the spirit of the advice
in the style guide and https://github.com/golang/go/wiki/CodeReviewComments#imports,
his change makes an effort to clean up and normalize import aliasing.

This change makes no API or behavioral changes. It is a pure cleanup intended
o help make the code more readable to developers (including myself) trying to
understand what is being imported where.

Only unexported names have been modified, and the changes were generated and
applied mechanically with gofmt -r and comby, respecting the lexical and
syntactic rules of Go.  Even so, I did not fix every inconsistency. Where the
changes would be too disruptive, I left it alone.

The principles I followed in this cleanup are:

- Remove aliases that restate the package name.
- Remove aliases where the base package name is unambiguous.
- Move overly-terse abbreviations from the import to the usage site.
- Fix lexical issues (remove underscores, remove capitalization).
- Fix import groupings to more closely match the style guide.
- Group blank (side-effecting) imports and ensure they are commented.
- Add aliases to multiple imports with the same base package name.

This is just a configuration change to default to using the new stack
unless explicitly disabled (e.g. `UseLegacy`) this renames the
configuration value and makes the configuration logic more clear.

The legacy option is good to retain as a fallback if the new stack has
issues operationally, but we should make sure that most of the time
we're using the new stack.

EDIT: Updated, see [comment below]( https://github.com/tendermint/tendermint/pull/6785#issuecomment-897793175)

This change adds a sketch of the `Debug` mode. 

This change adds a `Debug` struct to the node package. This `Debug` struct is intended to be created and started by a command in the `cmd` directory. The `Debug` struct runs the RPC server on the data directories: both the state store and the block store.

This change required a good deal of refactoring. Namely, a new `rpc.go` file was added to the `node` package. This file encapsulates functions for starting RPC servers used by nodes. A potential additional change is to further factor this code into shared code _in_ the `rpc` package. 

Minor API tweaks were also made that seemed appropriate such as the mechanism for fetching routes from the `rpc/core` package.

Additional work is required to register the `Debug` service as a command in the `cmd` directory but I am looking for feedback on if this direction seems appropriate before diving much further.

closes: #5908

* node: minimize hardcoded service initialization

* hacking

* nil safety

* reduce space

* remove genesis state store

* fix lint

* fix pex

* unwind some odering effects

* fix tests

* remove unused experiment

## Description

Remove v2 flag from toml

* docs: update events

* lint++

* lint++

## Description

Expose p2p functions for use in the sdk. 

These functions could also be copied over to the sdk. I dont have a preference of which is better.

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

Closes #3507

## Description

Add version back to versions, but allow it to be overridden via a ldflag.

Reason:

Many users are not setting the ldflag causing issues with tooling that relies on it (cosmjs)

closes #6488

cc @webmaster128