Animator start and stop notifications during seek

Bug: 259287604

Seeking an AnimatorSet with setCurrentPlayTime will notify
onAnimationStart() and onAnimationEnd() for itself and children,
regardless of whether the AnimatorSet has been started or not.

Test: new CTS tests
Change-Id: Ibb83f613184f64381c4629cad1858b3aab8bf90a
3 files changed