Add Integration Tests for App Jank Tracking

This change adds tests to verify the following:
  * Platform widgets can obtain a JankTracker object.
  * Platform widgets can report state changes that are tracked.
  * Call reportAppJankStats from a view and see an increase in
    pending stats count.
  * When activity is no longer visible jank tracking is paused.
  * When activity is resumed jank tracking is re-enabled.

Bug:377714256
Flag: android.app.jank.detailed_app_jank_metrics_api
Test: atest CoreAppJankTestCases:IntegrationTests

Change-Id: I6a80ea8e309983169deb44e30ab066f1d0576ff7