Add APIs for call connected indicator

When a call is connected, device can start playing a tone or vibrating
to prompt user the call status, especially when device is near to ear.

Test: manual
Test: atest RingerTest & CallConnectedIndicatorSettingsTest
Bug: 146090790
Bug: 405460896
Flag: com.android.server.telecom.flags.call_connected_indicator_preference

Change-Id: I8377a7c80e8125a7cf44573f86ce864d52872285