IMS: Propagate call session property changed message

- RTT Voice information will be passed to the UI via the call
  session property changed message

- The RTT voice information - SPEECH/SILENCE, will be conveyed
  via the Connection.PROPERTY_RTT_AUDIO_SPEECH bit mask in the
  call session property

- A connection event will be sent from frameworks to the UI -
  EVENT_CALL_PROPERTY_CHANGED

- Add listeners, connection event and extras to propagate the
  call session property to the UI

Change-Id: Iad68bb3964d15a612be7020a8c03c28825e4d371
CRs-Fixed: 2233887