Fix NSSL background flicker during dual shade display transition

The NSSL background flickered when moving the dual shade between displays.
This was primarily due to NSSL dimensions not updating while the shade was
briefly invisible during the transition.

This CL addresses this by:
- Avoiding collapsing/expanding the shade if the same section remains active,
  allowing new dimensions to apply immediately to the visible window.
- For different sections (e.g., QS vs. notifications), the shade is
  collapsed, then reparented. A frame wait after configuration change
  ensures the correct section expands without flicker, adding one frame of latency.

A potential remaining issue with NSSL background dimension updates from
DisplayStateRepository (due to onDisplayChanged event timing) will be
addressed in a subsequent CL.

Refactored ShadeDisplaysWaitInteractor.kt for use in multiple classes
(covered by existing tests).

Bug: 362719719
Bug: 417956803
Test: ShadeDisplaysInteractorTest, ShadeDisplayChangeLatencyTrackerTest
Flag: com.android.systemui.shade_window_goes_around
Change-Id: I8034f96d2f9d2e7ab3cf5d84d89a0f601c51d2f1