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).
This improves the `peerStore` prototype by e.g.:
* Using a database with Protobuf for persistence, but also keeping full peer set in memory for performance.
* Simplifying the API, by taking/returning struct copies for safety, and removing errors for in-memory operations.
* Caching the ranked peer set, as a temporary solution until a better data structure is implemented.
* Adding `PeerManagerOptions.MaxPeers` and pruning the peer store (based on rank) when it's full.
* Rewriting `PeerAddress` to be independent of `url.URL`, normalizing it and tightening semantics.
The `NodeInfo` interface does not appear to serve any purpose at all, so I removed it and renamed the `DefaultNodeInfo` struct to `NodeInfo` (including the Protobuf representations). Let me know if this is actually needed for anything.
Only the Protobuf rename is listed in the changelog, since we do not officially support API stability of the `p2p` package (according to `README.md`). The on-wire protocol remains compatible.
## 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
Erik Grinaker
Marko