Merge "Add toast instructing user to select second split app" into sc-v2-dev am: 31e400d62e

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/15925826

Change-Id: I22f1a08cf06cfc0e9b374b12b8c4265ccad6e77b