Reject incoming call for emergency call

An emergency call fails when receiving a call at the same time.
Reject incoming call before dialing an emergency call in ringing state.

Bug: 325705941
Test: atest TelephonyConnectionServiceTest
Manual test:
1. Make a call from A to DUT.
2. Check whether the call is in alerting state in A.
3. At that moment, dial 911 in DUT before the incoming call is notified.
Change-Id: I56e3f38d9fad23ef9de99bdc6932c132f47d9bfe
2 files changed