Bluetooth: Enable in-band ringing in vibration mode (4/4)

* Add RINGER_MODE_CHANGE message in CallAudioModeStateMachine to re-try
  startRinging() in RingingFocus state
* When HFP is connected, CallAudioRouteStateMachine will notify
  CallAudioModeStateMachine about new established SCO connection.
  CallAudioModeStateMachine will try to start playing ringtone at such
  event in case ringtone volume condition changes
* Added and adjusted unit tests in CallAudioRouteStateMachineTest,
  CallAudioModeStateMachineTest and CallAudioRouteTransitionTests

Bug: 72647074
Test: Call phone in vibration mode and hear ringtone on HFP enabled
      headset, verify that ringtone is only played through headset.
      Then disconnect headset and call again to verify that ringtone
      does not play through phone speaker in vibration mode.
      Telecom unit tests: lite_test_telecom

Change-Id: Ie00059213292005c3e3af0c771c148ec0dc22498
(cherry picked from commit fff818b3cd1f8ba91a5037bcb91b5478a5663a25)