[1/N] APIs of verification service, session and status

+ Feature flag
+ APIs for VerifierService, VerificationSession, VerificationStatus
+ AIDL interfaces for binder communication
+ Unit testing

BUG: 360129103
FLAG: android.content.pm.verification_service
Test: atest FrameworksCoreTests:android.content.pm.verify.VerificationSessionTest
Test: atest FrameworksCoreTests:android.content.pm.verify.VerificationStatusTest
Test: atest FrameworksCoreTests:android.content.pm.verify.VerifierServiceTest
Test: cts tests to be added
API-Coverage-Bug: 367776952

Change-Id: Ide0b060d1ba61f3a9f53a6b87240df5045cd46eb