Add IntrusionDetectionEventTransport class to provide a

stable-API bridge between IIntrusionDetectionEventTransport
and its implementations.

Bug: 369313906
Change-Id: I899f22ce8a4c10274c12e5d535a599d667036df6
Test: m -j ; atest IntrusionDetectionServiceTest
Flag: android.security.afl_api
Ignore-AOSP-First: security feature
API-Coverage-Bug: 378004596