Add a gRPC connector to backfila

[ThePumpingLemma]

No description provided.

[mpawliszyn]

I think we don't want the Backfila grpc service?

Otherwise I would think we would need to do more to the guice config to configure it properly?

Also what about the path that GRPC would use? Or does that no longer matter?

[mpawliszyn]

I'm not sure we need this unless we want people to use GRPC to talk to Backfila as well.

[ThePumpingLemma]

Yeah, I debated whether or not we should add this from a symmetry perspective. Don't feel strongly either way, but it would be nice to support gRPC bidirectionally in the future (since we standardized on it internally).

[ThePumpingLemma]

I think we don't want the Backfila grpc service?

Otherwise I would think we would need to do more to the guice config to configure it properly?

Yeah, this is more aspirational currently. Not 100% sure how to wire up an additional gRPC variant in Misk.

Also what about the path that GRPC would use? Or does that no longer matter?

gRPC doesn't need paths (the path is effectively specified by the package name), we just need to specify the authority for the client.