Merge "Implement pressing back button and swiping back" into sc-v2-dev am: 97d74983 am: 4c818e40

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/16013509

Change-Id: Ie7e6b573de7b75786eb3852d81f88292009ab5b6