Have Telecom service notify AudioService of RTT call state.

Calculate RTT call state when:
- a call is added
- a call is removed
- a call's CallState is changed
- a call's RTT connection property is changed
and notify AudioServer of the RTT call state change.

Bug: 147037345
Test: Force installed Gboard 8.3.6 and verified voice typing works in
  simulated RTT call and simulated RTT upgrade call.
Change-Id: I78b93ce42474b7fc28f7193afee2a6328e2abfd0