Merge "Add ENABLE_SCRIM_FOR_APP_LAUNCH feature flag." into sc-dev am: 28e39335bc am: c01e87daf0

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/14987185

Change-Id: I838a99b25e4ed3574e451ec752c12d517eda05b1