Merge "SystemUI proxy updates for managing split screen" into sc-dev am: b93119e3b9

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/apps/Launcher3/+/13732341

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I5becd458eed4a24cf6a0bd36ed4e55ed5d0b473f