Closes https://github.com/tendermint/tendermint/issues/3857

Moves `lib/` folder to `jsonrpc/`.

Renames:

**packages**

`rpc` package -> `jsonrpc` package
`rpcclient` package -> `client` package
`rpcserver` package -> `server` package

**structs and interfaces**

```
JSONRPCClient to Client
JSONRPCRequestBatch to RequestBatch
JSONRPCCaller to Caller
```

**functions**

```
StartHTTPServer to Serve
StartHTTPAndTLSServer to ServeTLS

rpc/jsonrpc/client: rename NewURIClient to NewURI

NewJSONRPCClient to New
NewJSONRPCClientWithHTTPClient to NewWithHTTPClient
NewWSClient to NewWS
```

**misc**

- unexpose `ResponseWriterWrapper`
- remove unused http_params.go

Closes #3433

* Added BlockStore.DeleteBlock()

* Added initial block pruner prototype

* wip

* Added BlockStore.PruneBlocks()

* Added consensus setting for block pruning

* Added BlockStore base

* Error on replay if base does not have blocks

* Handle missing blocks when sending VoteSetMaj23Message

* Error message tweak

* Properly update blockstore state

* Error message fix again

* blockchain: ignore peer missing blocks

* Added FIXME

* Added test for block replay with truncated history

* Handle peer base in blockchain reactor

* Improved replay error handling

* Added tests for Store.PruneBlocks()

* Fix non-RPC handling of truncated block history

* Panic on missing block meta in needProofBlock()

* Updated changelog

* Handle truncated block history in RPC layer

* Added info about earliest block in /status RPC

* Reorder height and base in blockchain reactor messages

* Updated changelog

* Fix tests

* Appease linter

* Minor review fixes

* Non-empty BlockStores should always have base > 0

* Update code to assume base > 0 invariant

* Added blockstore tests for pruning to 0

* Make sure we don't prune below the current base

* Added BlockStore.Size()

* config: added retain_blocks recommendations

* Update v1 blockchain reactor to handle blockstore base

* Added state database pruning

* Propagate errors on missing validator sets

* Comment tweaks

* Improved error message

Co-Authored-By: Anton Kaliaev <anton.kalyaev@gmail.com>

* use ABCI field ResponseCommit.retain_height instead of retain-blocks config option

* remove State.RetainHeight, return value instead

* fix minor issues

* rename pruneHeights() to pruneBlocks()

* noop to fix GitHub borkage

Co-authored-by: Anton Kaliaev <anton.kalyaev@gmail.com>

* format: add format cmd & goimport repo

- replaced format command
- added goimports to format command
- ran goimports

Signed-off-by: Marko Baricevic <marbar3778@yahoo.com>

* fix outliers & undo proto file changes

* added RPC method block_by_hash

* created hash => height

* changes typings

* block_by_hash changes

* Update store/store.go

Co-Authored-By: Anton Kaliaev <anton.kalyaev@gmail.com>

* Update store/store.go

Co-Authored-By: Anton Kaliaev <anton.kalyaev@gmail.com>

* Update store/store.go

Co-Authored-By: Anton Kaliaev <anton.kalyaev@gmail.com>

* Update store/store.go

Co-Authored-By: Anton Kaliaev <anton.kalyaev@gmail.com>

Co-authored-by: Marko <marbar3778@yahoo.com>
Co-authored-by: Anton Kaliaev <anton.kalyaev@gmail.com>

BREAKING

Example response:

```json
{
  "jsonrpc": "2.0",
  "id": "",
  "result": {
    "height": "2109",
    "txs_results": null,
    "begin_block_events": null,
    "end_block_events": null,
    "validator_updates": null,
    "consensus_param_updates": null
  }
}
```

Old result consisted of ABCIResponses struct and height. Exposing
internal ABCI structures (which we store in state package) in RPC seems
bad to me for the following reasons:

1) high risk of breaking the API when somebody changes internal structs
(HAPPENED HERE!)
2) RPC is aware of ABCI, which I'm not sure we want