Fixes#5899 by renaming a bunch of P2P Protobuf entities (while maintaining wire compatibility):
* `Message` to `PexMessage` (as it's only used for PEX messages).
* `PexAddrs` to `PexResponse`.
* `PexResponse.Addrs` to `PexResponse.Addresses`.
* `NetAddress` to `PexAddress` (as it's only used by PEX).
Reorganizes the Protobuf schemas. It is mostly bikeshedding, so if something is contentious or causes a lot of extra work then I'm fine with reverting. Some Protobuf and Go import paths will change.
* Move `abci/types/types.proto` to `abci/types.proto`.
* Move `crypto/keys/types.proto` and `crypto/merkle/types.proto` to `crypto/keys.proto` and `crypto/proof.proto`.
* Drop the use of `msgs` in filenames, as "message" is a very overloaded term (all Protobuf types are messages, and we also have `message Message`). Use `types.proto` as a catch-all, and otherwise name files by conceptual grouping instead of message kind.
## Description
This PR moves all proto files under one dir (`/proto`). The script to generate adding functionality to copy the files that still need to be in the same place. (abci & rpc)
renames every proto package from `tendermint.proto.<pkg_name>` to `tendermint.<pkg_name>`
Removes unneeded types in privval proto directory
Closes: #XXX
Callum Waters
Erik Grinaker
Marko