=per #3933 Correction of seq number logic for persistent channel (backport)

* Problem when using PersistentChannel from Processor
* When the seq numbers of the sending processor and the seq numbers
  of the PersistentChannel was out of sync the PersistentChannel
  did not de-duplicate confirmed deliveres that were resent by
  the processor.
* There is a hand-off in the RequestWriter that confirms the
  Processor seq number, and therefore the seq number of the
  RequestWriter must be used in the ConfirmablePersistent from
  the RequestReader
* More tests, covering this scenario

(cherry picked from commit c7e157121ac6f49bdbdf0cc659d28b80095a807d)