Investigate feasibility of switching to proto-lens for protobuf serialization.

[patrickt]

For historical reasons, we depend on forked versions of proto3-suite and proto3-wire. It would be pretty ideal if we could switch to proto-lens, given its somewhat nicer API and the fact that we don’t use any gRPC features that proto3-suite provides.

[patrickt]

Obviously, we can’t break backwards compatibility here, so it needs to be done very carefully.

[jkachmar]

Relevant modules from proto-lens as they relate to RPC service declaration:

• Service types and classes
• Example .proto file with different RPC types
• Test demonstrating the types generated from the aforementioned .proto file

Since proto-lens provides a protoc plugin you may be able to use that directly instead of however the proto3-suite stuff gets generated.

From there, I imagine there’s enough information to generate any actual implementation code wiring those RPC definitions up to server/client handlers with TemplateHaskell or Generic derivation (to potentially avoid having to write more protoc stuff).