Start PiP dismiss from SysUI via TaskOrganizer

following ag/10570572, dismiss PiP is driven by SysUI as following
- SysUI issues WindowContainerTransaction and set the child windowing
mode at the beginning
- SysUI continues the animation
- SysUI issues WindowContainerTransaction and set the final windowing
mode at the end

This solves also the black background issue while exiting from PiP to
fullscreen mode.

Known issues
- app does not receive fullscreen configuration when transitioning from
PiP to fullscreen mode
- saving of the reentry bounds should be originated from SysUI rather
than WM going forward

Bug: 149947030
Bug: 151866274
Test: atest PinnedStackTests PipAnimationControllerTest
Change-Id: I7ed0d8b47dcc26653ebe2f3c08acab9e8b835db4