Merge "Make split screen have enter and exit animation" into tm-qpr-dev am: c6bffbb3

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/20490027



Change-Id: I544edae7a1f43656474b4486a698240d4869c9dc
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>