[flexiglass] Require single swipe up to return to LS from QS scene

Utilizes the previousScene flow to build the destination scenes for the
QS scene.

Fix: 330695017
Test: unit test added
Test: manually verified that, when the device is locked and the QS scene
is opened with a two finger swipe-down from near the top edge of the
screen, hitting back or swipine up while on the QS scene, correctly
returns to the locscreen scene and not the shade scene
Test: manually verified that when arriving to the QS scene from the
shade scene via normal swipe down, back/up returns to the shade scene
Test: manually verified that, when the device is NOT locked and the QS scene
is opened with a swipe-down from near the top edge of the
screen, hitting back or swipine up while on the QS scene, correctly
returns to the gone scene and not the shade scene
Flag: ACONFIG com.android.systemui.scene_container DEVELOPMENT

Change-Id: Iae554155e5c3bd2a9b673c1b9d0a21ba7b60943e