Pattern based publish for topics/service keys

[johanandren]

Related to akka/akka-projection#1128

While thinking of about we could implement that, I came to this idea of how we can do type safe broadcast: the receptionist knows the service keys, the service keys knows the the protocol type (or was there some problem with that for topics?), so we could perhaps do a pattern/wildcard match on service keys and and message type, and do a wildcard broadcast.