Move to more efficient message format

[realityforge]

Currently, we a hand-written json format that is inefficient at runtime and costly to maintain. We should consider moving to an external wire-format that is fast, binary.

Candidates include:

• CBOR which is a standard and has several implementations
• Alternatively protobufs from google seems like a popular alternative
  • https://github.com/dcodeIO/protobuf.js
  • Or even better and faster - Capt Proto - https://capnproto.org/language.html
  • Or Protobuf+gRPC = https://www.cncf.io/blog/2018/10/24/grpc-web-is-going-ga/

[realityforge]

It seems like the most runtime and transport size efficient form is Flatbuffers which has no generated javascript form (but could have one based on TypedArray if we desired) while a protobuf variant with generated types seems easiest to use, if slightly less efficient.