Add tests that activity can receive ACTION_CANCEL after onBackStarted

Add tests for
1. Activity not opt-in predictive back
2. Activity opt-in predictive back and
   - with default onBackInvokedCallback
   - register it's own onBackInvokedCallback
The activity should receive ACTION_CANCEL in above conditions once the
back gesture across the threshold.

Flag: com.android.window.flags.intercept_motion_from_move_to_cancel
Bug: 404173501
Test: atest OnBackInvokedCallbackGestureTest
Change-Id: Ia63d4f886e02206c32094791ae5badd0b65e658a
4 files changed