+per #15424 Added PersistentView, deprecated View

A PersistentView works the same way as View did previously, except:

* it requires an `peristenceId` (no default is provided)
* messages given to `receive` are NOT wrapped in Persistent()

akka-streams not touched, will update them afterwards on different branch

Also solves #15436 by making persistentId in PersistentView abstract.

(cherry picked from commit dcafaf788236fe6d018388dd55d5bf9650ded696)

Conflicts:
	akka-docs/rst/java/lambda-persistence.rst
	akka-docs/rst/java/persistence.rst
	akka-docs/rst/scala/persistence.rst
	akka-persistence/src/main/scala/akka/persistence/Persistent.scala
	akka-persistence/src/main/scala/akka/persistence/View.scala
Merge pull request #15450 from akka/wip-15424-master-patriknw

+per #15424 Added PersistentView, deprecated View (for validation)