Merge "[DO NOT MERGE] Animate dialog stack and use in UserSwitcher" into sc-v2-dev am: 4ad4975b28

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/16244707

Change-Id: I3356d00cb1e61d1339da900d1c2910cb0bcfb0be