=sam #12702 Create FsmSimpleRedelivery sample

This one is created instead of the batching pattern of #12702, as suggested by @ktoso in #12702's discussion.

Should it get some tests, as stated in `CONTRIBUTING.md`? I'm asking, because most other samples seem not to be tested at all. =)

Also, I'm not quite sure why Scalariform did not change `=>` into its UTF-8 counterpart. Sbt says it is running it at each compilation...
Would be nicer as:

```scala
object FsmSimpleRedelivery extends App {
implicit val system = ActorSystem()
system.actorOf(Requester.props)
// ... 
}