With the current gRPC design the CA talks directly to the Publisher when calling SubmitToCT which crosses security bounadries (secure internal segment -> internet facing segment) which is dangerous if (however unlikely) the Publisher is compromised and there is a gRPC exploit that allows memory corruption on the caller end of a RPC which could expose sensitive information or cause arbitrary issuance.
Instead we move the RPC call to the RA which is in a less sensitive network segment. Switching the call site from the CA -> RA is gated on adding the gRPC PublisherService object to the RA config.
Fixes#2202.
c5f99453a9