Merge "Launch overview as transient" into sc-dev am: 3f4333bfa1 am: aa333f4e7e

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/14444777

Change-Id: I5c77a8ef9e5989274c1afc3d26407898cb00e8e6