This adds protoc, protoc-gen-go, and protoc-gen-go-grpc to the list of
sg setup dependencies. They are not used yet, but will be required once
we have generated gRPC files.
Dependencies are as documented here.
I've tested that these are the minimum set of dependencies needed to generate gRPC
services from .proto files.
Test plan
Manually tested that the checks and auto-fix work on my MacOS machine.
