Deprecate actorFor in favor of ActorSelection, see #3074

* Deprecate all actorFor methods
* resolveActorRef in provider
* Identify auto receive message
* Support ActorPath in actorSelection
* Support remote actor selections
* Additional tests of actor selection
* Update tests (keep most actorFor tests)
* Update samples to use actorSelection
Update cluster sampes to use actorSelection, see #3074
A few updates to documentation, see #3074
Fix issue from merge, see #3074
Updates to documentation, see #3074
Remove UnknownActorIdentity, see #3074