Refactor nodejs compilation from genrule to full bazel rule

[Phillammon]

Problem to solve
The nodejs genrule is cumbersome, and also requires exposing the raw .proto files with a filegroup instead of accessing via the proto_library rules provided.

Proposed solution
Rewrite the genruled as a full fledge bazel rule, including accessing the source files via proto_library.src_file, and delete the associated filegroup from the /proto/BUILD file

[flyingsilverfin]

This is still a valid issue and represents a significant awkwardness in the NodeJS protobuf compilation process