Ensure that the peer stream replication rpc can successfully be used with TLS activated.
Also:
- If key material is configured for the gRPC port but HTTPS is not
enabled now TLS will still be activated for the gRPC port.
- peerstream replication stream opened by the establishing-side will now
ignore grpc.WithBlock so that TLS errors will bubble up instead of
being awkwardly delayed or suppressed
Previously, public referred to gRPC services that are both exposed on
the dedicated gRPC port and have their definitions in the proto-public
directory (so were considered usable by 3rd parties). Whereas private
referred to services on the multiplexed server port that are only usable
by agents and other servers.
Now, we're splitting these definitions, such that external/internal
refers to the port and public/private refers to whether they can be used
by 3rd parties.
This is necessary because the peering replication API needs to be
exposed on the dedicated port, but is not (yet) suitable for use by 3rd
parties.