In (*PeerState).PickSendVote, there is a Debug-level log that includes the PeerState value as a logging field. By default, zerolog json-encodes a struct passed as a log field (when the struct doesn't implement zerolog.LogObjectMarshaler).

Because PeerState didn't have a MarshalJSON method, the JSON encoder fell back to reflection to encode the PeerState value. Reflection did not acquire the lock, and there were data races resulting from an unsynchronized read while logging the PeerState, and concurrent (locked) writes at least during (*PeerState).SetHasProposal and (*PeerState).SetHasVote.

Given that there was only one call to (*PeerState).ToJSON in the cometbft repo, it seemed appropriate to just rename ToJSON to MarshalJSON, as opposed to leaving ToJSON for backwards compatibility. Any third party calls to ToJSON should be able to easily change the method being called.

Example data race (which is no longer reproducible with this change):

```
==================
WARNING: DATA RACE
Read at 0x00c0004a4870 by goroutine 131:
  reflect.Value.Bool()
      /opt/homebrew/Cellar/go/1.20.1/libexec/src/reflect/value.go:288 +0x7c
  encoding/json.boolEncoder()
      /opt/homebrew/Cellar/go/1.20.1/libexec/src/encoding/json/encode.go:539 +0x88
  encoding/json.structEncoder.encode()
      /opt/homebrew/Cellar/go/1.20.1/libexec/src/encoding/json/encode.go:759 +0x1bc
  encoding/json.structEncoder.encode-fm()
      <autogenerated>:1 +0x94
  encoding/json.structEncoder.encode()
      /opt/homebrew/Cellar/go/1.20.1/libexec/src/encoding/json/encode.go:759 +0x1bc
  encoding/json.structEncoder.encode-fm()
      <autogenerated>:1 +0x94
  encoding/json.ptrEncoder.encode()
      /opt/homebrew/Cellar/go/1.20.1/libexec/src/encoding/json/encode.go:943 +0x2a4
  encoding/json.ptrEncoder.encode-fm()
      <autogenerated>:1 +0x6c
  encoding/json.(*encodeState).reflectValue()
      /opt/homebrew/Cellar/go/1.20.1/libexec/src/encoding/json/encode.go:358 +0x74
  encoding/json.(*encodeState).marshal()
      /opt/homebrew/Cellar/go/1.20.1/libexec/src/encoding/json/encode.go:330 +0x1a0
  encoding/json.Marshal()
      /opt/homebrew/Cellar/go/1.20.1/libexec/src/encoding/json/encode.go:161 +0xa0
  github.com/rs/zerolog.init.1.func1()
      /Users/hh/go/pkg/mod/github.com/rs/zerolog@v1.29.0/encoder_json.go:21 +0x4c
  github.com/rs/zerolog/internal/json.Encoder.AppendInterface()
      /Users/hh/go/pkg/mod/github.com/rs/zerolog@v1.29.0/internal/json/types.go:366 +0x5c
  github.com/rs/zerolog.appendFieldList()
      /Users/hh/go/pkg/mod/github.com/rs/zerolog@v1.29.0/fields.go:273 +0x2b8c
  github.com/rs/zerolog.appendFields()
      /Users/hh/go/pkg/mod/github.com/rs/zerolog@v1.29.0/fields.go:21 +0x160
  github.com/rs/zerolog.(*Event).Fields()
      /Users/hh/go/pkg/mod/github.com/rs/zerolog@v1.29.0/event.go:165 +0x90
  cosmossdk.io/log.zeroLogWrapper.Debug()
      /Users/hh/go/pkg/mod/cosmossdk.io/log@v0.0.0-20230313123454-0fe816b71a62/logger.go:89 +0x18
  github.com/cosmos/cosmos-sdk/server/log.(*CometZeroLogWrapper).Debug()
      <autogenerated>:1 +0x74
  github.com/cometbft/cometbft/consensus.(*PeerState).PickSendVote()
      /Users/hh/go/src/github.com/cometbft/cometbft/consensus/reactor.go:1138 +0x1bc
  github.com/cometbft/cometbft/consensus.(*Reactor).gossipVotesForHeight()
      /Users/hh/go/src/github.com/cometbft/cometbft/consensus/reactor.go:794 +0x260
  github.com/cometbft/cometbft/consensus.(*Reactor).gossipVotesRoutine()
      /Users/hh/go/src/github.com/cometbft/cometbft/consensus/reactor.go:724 +0x2cc
  github.com/cometbft/cometbft/consensus.(*Reactor).AddPeer.func2()
      /Users/hh/go/src/github.com/cometbft/cometbft/consensus/reactor.go:199 +0x58

Previous write at 0x00c0004a4870 by goroutine 130:
  github.com/cometbft/cometbft/consensus.(*PeerState).SetHasProposal()
      /Users/hh/go/src/github.com/cometbft/cometbft/consensus/reactor.go:1096 +0x118
  github.com/cometbft/cometbft/consensus.(*Reactor).gossipDataRoutine()
      /Users/hh/go/src/github.com/cometbft/cometbft/consensus/reactor.go:617 +0xab8
  github.com/cometbft/cometbft/consensus.(*Reactor).AddPeer.func1()
      /Users/hh/go/src/github.com/cometbft/cometbft/consensus/reactor.go:198 +0x58

Goroutine 131 (running) created at:
  github.com/cometbft/cometbft/consensus.(*Reactor).AddPeer()
      /Users/hh/go/src/github.com/cometbft/cometbft/consensus/reactor.go:199 +0x240
  github.com/cometbft/cometbft/p2p.(*Switch).addPeer()
      /Users/hh/go/src/github.com/cometbft/cometbft/p2p/switch.go:855 +0x7b4
  github.com/cometbft/cometbft/p2p.(*Switch).acceptRoutine()
      /Users/hh/go/src/github.com/cometbft/cometbft/p2p/switch.go:707 +0x704
  github.com/cometbft/cometbft/p2p.(*Switch).OnStart.func1()
      /Users/hh/go/src/github.com/cometbft/cometbft/p2p/switch.go:241 +0x34

Goroutine 130 (running) created at:
  github.com/cometbft/cometbft/consensus.(*Reactor).AddPeer()
      /Users/hh/go/src/github.com/cometbft/cometbft/consensus/reactor.go:198 +0x164
  github.com/cometbft/cometbft/p2p.(*Switch).addPeer()
      /Users/hh/go/src/github.com/cometbft/cometbft/p2p/switch.go:855 +0x7b4
  github.com/cometbft/cometbft/p2p.(*Switch).acceptRoutine()
      /Users/hh/go/src/github.com/cometbft/cometbft/p2p/switch.go:707 +0x704
  github.com/cometbft/cometbft/p2p.(*Switch).OnStart.func1()
      /Users/hh/go/src/github.com/cometbft/cometbft/p2p/switch.go:241 +0x34
==================
```

---

#### PR checklist

- [ ] Tests written/updated
- [x] Changelog entry added in `.changelog` (we use [unclog](https://github.com/informalsystems/unclog) to manage our changelog)
- [ ] Updated relevant documentation (`docs/` or `spec/`) and code comments

(cherry picked from commit 587bc0b)