[Rendezvous] Protobuff class generation as part of packing

[da-kami]

Trigger the proto-classes code generation on webpack build as optimization.

For #174 protobuf message classes are generated using protobuf.js CLI:
Run yarn run pbjs -t static-module -o src/proto.js src/rpc.proto to generate the javascript code.
Run yarn run pbts -o src/proto.d.ts src/proto.js to generate types for the generated javascript code.

Currently the generated code is just added to the repository.