[bc25] Refactor ShadeInteractor for Dual Shade Overlays.

This also adds expandNotificationShade() and expandQuickSettingsShade(),
 which make it easier to ensure the shade is opened correctly in the
 different shade modes.

Bug: 356596436
Flag: com.android.systemui.scene_container
Flag: com.android.systemui.dual_shade
Test: Manually tested by opening the Wallpaper Picker and navigating to
 the "Lock screen" tab and "Shortcuts" section. The lockscreen preview
 renders correctly, and the shortcuts change and render correctly too.
Test: Added new unit tests for the two new functions introduced.
Test: Existing unit tests still pass.
Change-Id: I92368206c6849c8fefba881049db391d8ca9b11f