Support for override active D2D transport.

Adding support for overriding the active D2D transport.
Also adding more log messages.
And wire in received DTMF messages into TelephonyConnection.
Prevent D2D for emergency calls.

Test: Manual testing with two devices.
Test: Manual test with test emergency numbers.
Test: Run D2D unit tests.
Bug: 163085177
Change-Id: I5f971fcfc49a86388ed17e1774baf44d920de9b7
4 files changed