[PiP2] Respond to AppOps change in PiP2

Integrate the PipAppOpsListener into PiP2 and make it independent from
PipTouchHandler / PipMotionHelper.

Flag: com.android.wm.shell.enable_pip2
Bug: 381190353
Video: http://recall/-/aaaaaabFQoRHlzixHdtY/eHQTWNTeGScZpJYzI4liOM
Test: Turn off app ops settings, verify pip vanishes, see video
Test: atest WMShellUnitTests:PipAppOpsListenerTest
Change-Id: Iafbd43e403b07d9ca9d22b54bd665ec2ec70efcd