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: Ie5f25acb72f2682e1256a0f80231761a1532e30f