=str #16095 make Actor{Publisher,Subscriber} as {Source,Sink}

* Props{Source,Sink} creates an actor from props as a child
of StreamSupervisor actor and wraps it into {Publisher,Subscriber}.
Actor should be one of akka.stream.actor.Actor{Publisher,Subscriber}
Merge pull request #16119 from 2m/wip-actor-pub-sub-source-sink-16095

=str #16095 make Actor{Publisher,Subscriber} as {Source,Sink}