Make PiP window functional after moving displays.

Demo: https://drive.google.com/file/d/10p1WIkcYVgERWVNnGmtJxqZOGjHXAPkM/view?usp=sharing

Bug: 383403514
Test: manual test and atest
Flag: com.android.window.flags.enable_dragging_pip_across_displays
Change-Id: I6a7e2e3a76afa5e1e60554b16b539b940264a920