Fix issues with z-ordering during animations

- Make sure to use DC pending transaction when updating z-layers,
as it could lead to reordering of z-order assignment due to how
we apply pending transactions in the hierarchy

- Create a separate boosted animation layer in which AWT with
zOrder=top animate, which happens above all stack. This brings
back the boosting logic in O without boosting non-boosted stack
above non-animating tokens

Bug: 70730519
Bug: 72649981
Bug: 72686618
Bug: 37953606
Test: Share link from Chrome to Clipboard, make sure disappear
animation happens properly
Test: go/wm-smoke
Change-Id: I3957daac76b991402bf3f520c4a3d3f519933f72