new class AudioRouter manages audio routing for the phone call

This CL only has support between bluetooth/earpiece

Of Note:
- New shared class AudioMode defines different modes for audio routing
- New class AudioRouter manages between EARPIECE and Bluetooth modes.
- Add function in CallCommandService and CallHandlerService for audio
  mode

Change-Id: I52ff70e53868c45e5202b757cc80a13af3abe5f8
8 files changed