[flexiglass] StatusBarStateController uses scene framework.

Makes StatusBarStateController treat Flexiglass as its upstream source
of truth for the StatusBarState state, if Flexiglass is on.

Fix: 323187006
Test: manually verified that locking, unlocking, and expanding the shade
and QS emitted the same StatusBarState values with Flexiglass on and
with Flexiglass off.
Flag: ACONFIG com.android.systemui.scene_container DEVELOPMENT

Change-Id: I5e827ec4f2ed8503b03d09d428604635fe5dd1ac