Need interface for vendor ImsService to know about phone process crash

Need interface for vendor ImsService to know about phone process crash.
ImsService recognizes phone process crash, clear all resource internally.

Bug: 224481029
Test: atest ImsServiceTest
Test: manual test with AT&T SIM
1. device boot up
2. after IMS registration
3. kill phone process in adb shell
4. check log

Change-Id: I773195d4bc71dddd6efba8e1de5d6d4e6fb4e5c7