Merge "Add task unpinning support for 3 button taskbar" into sc-v2-dev am: f198f6e492 am: b3f069e06c

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/16339859

Change-Id: Ifb1a086f3a93f14ee7a8889c110b991c7b7701d9