Fix touch goes to the window behide PiP

When an Acitivty enter PictureInPicture mode, the pip input consumer
would be created and show the PipMenuActivity at first entry
(MENU_STATE_CLOSE) or show full menu (MENU_STATE_FULL) if user clicks
the pip window.

So in order to control the pip wndow dragging and menu, the pip input
consumer would be destoryed when menu window has shown, and it would be
created when the pip window starts to drag or the menu has hidden.
And the menu window should also has the flag FLAG_SLIPPERY to make sure
touch can through to the pip input consumer, but it could not guarantee
which window can receive the touch.

This patch would make sure all touch events except ACTION_OUTSIDE can
go through pip input consumer because it's above the pip window and it
can integrate all behaviors like window dragging or show menu in
PipTouchHandler without doing same thing and adding FLAG_SLIPPERY in
PipMenuActivity.

Test: atest PinnedStackTests
Test: atest SystemUITests
Bug: 139805619
Change-Id: I35f9eba867561168384d0a0d6c0608a6dbdf6a09