Move Bubbles into a hw-accelerated TYPE_APPLICATION_OVERLAY WindowManager layer.

This addresses several issues caused by Bubbles living in the status bar window and makes it easier to address several more open bugs.

Test: atest SystemUITests
Test: manually, a lot
Fixes: 130579263
Fixes: 142075351
Fixes: 151086286
Fixes: 149473357
Bug: 150906076
Change-Id: I61594931cce55cba78e6cb1fcec440e4fec32bb0