Clarify content vs identity in some instances

Address feedback

Use only major.minor for versions.

Rebase on master, again

I'm not sure the best path forward for handling the dynamodb logic, but in time I'm sure we will become more clear.

Nevermind, the struct is used to also hold the login state later on.

Rust looks fine to me

Might be nice to factor out all of the failable s3 code, which returns an s3 error, then we can just assert the error once from the calling code.

Rebase on latest master

Rebase on latest master

Rebase on latest master

identity -> grpc

Remove usage of "Comm"

This was rebased on top of deleting the old tunnelbroker.proto. Which is why I had it as something else originally.

Address feedback

Rebase on changes

Fixup comment

Use service agnostic protobuf

Rename protobuf file

Make service-agnostic

CMake looks fine to me, defer to others for the rest

Shouldn't matter if the message is opaque to the Tunnelbroker service

If we ever need some other internal service to send a message via Tunnelbroker, we won't need to update the .proto

Decision to create a separate service specifically for service A to talk to service B, versus just a unified service definition for service B