[PiP2] Add PipEnterAnimatorTest

Added the PipEnterAnimatorTest for PipEnterAnimator class.
PipEnterAnimator class is optimized for testing as well in this change

- Cleanup the supply of source rect hint, which deprecated from the
  previous refactor
- Allow supplying SurfaceControlTransactionFactory for testing purpose
- Allow supplying PipAppIconOverlay for testing purpose
- Use the local animation listener since they are implementation details
- Switch over to AnimatorListenerAdapter to avoid unnecessary,
  un-testable functions such as onAnimationRepeat
- Cleaned up the unused source rect hint param in PipEnterAnimator ctor

Flag: com.android.wm.shell.enable_pip2
Bug: 376133026
Test: atest WMShellUnitTests:PipEnterAnimatorTest
Change-Id: I1cb619505001ae1bc30fd8120a2cf750af2fb906