New ContentCapture constant: ActivityEvent.TYPE_ACTIVITY_DESTROYED

Test: m update-api
Test: atest ChildlessActivityTest#testLaunchAnotherActivity_onTopOfIt
Test: atest CtsContentCaptureServiceTestCases # sanity check
Fixes: 128904560

Change-Id: I32169c6a74d834858d8e22ec6adeb478b676bece
4 files changed