Add UNDEFINED KTF state and tie it to STL transitions

UNDEFINED is a special state that is always tied to STL transitions. It
is important that STL and KTF stay in-sync at all times. To guarantee
this UNDEFINED state is only controlled by
LockscreenSceneTransitionInteractor.

Test: LockscreenSceneTransitionInteractorTest
Test: Manual testing. Navigated around scenes and observed in logcat
 that KTF is following around correctly.
Bug: b/330311871
Bug: b/336581871
Flag: ACONFIG com.android.systemui.scene_container DEVELOPMENT
Change-Id: I2f9795415eef0ecd64a6181d2599b170af95866c