Merge "[flexiglass] Composables for scenes and scene container." into udc-dev am: c7814a5d am: 44da6241 am: 6c14a932 am: 097f650e

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/23067065



Change-Id: Ic30817c740ad8a5e88d173d31a237fd5945b2854
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>