chan_pjsip: Transmit REFER waits for the REFER result setting TRANSFERSTATUS

Previously, when a Transfer (REFER) was performed, chan_pjsip would set
the TRANSFERSTATUS to SUCCESS when the REFER was queued up.  This did not
reflect a successful/unsuccessful transfer the way chan_sip did.
Added a callback module to process the refer subscription information.

Now depends on res_pjsip_pubsub so call transfer progress can be monitored
and reported

ASTERISK-26968 #close
Reported-by: Dan Cropp

Change-Id: If6c27c757c66f71e8b75e3fe49da53ebe62395dc