Merge "Fade in/out taskbar bg alpha when unstash/stashing." into udc-dev am: 613cc95c8a am: 004ed77d11

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/23696768

Change-Id: I7ed64a239bff6254151032758bc8ca9cff360c49
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>