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

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

Change-Id: Id2c29bdcbc43f6e2f556a2b43f882c4dc24ec3e9