Merge "Add support for floating IME to split-screen" into rvc-dev am: 3d4bab48 am: d395f428 am: 313b4ff1

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/11932146

Change-Id: I4811a0e05617c9b4ffafaa0dfbd87f7dd7aa8679