Support multi-window status bar orchestration in Wear Material3 scaffolds.

AppScaffold previously assumed all screens shared the Activity host
window. However, Dialogs create separate Windows with distinct
DecorViews, causing AppScaffold to control the background Activity
window instead of the active Dialog window. Key changes:
- Pass `LocalView.current` from ScreenScaffold/PagerScaffold and AppScaffold to track window associations.
- Unify and cache `StatusBarOrchestrator` instances in ScreenContent by root view (`view.rootView ?: view`), ensuring screens in the same window share an orchestrator while Dialogs get their own.
- Route AppScaffold's status bar show/hide updates dynamically to the active top screen's window orchestrator (falling back to the host window).
- Automatically restore initial status bar state and detach listeners when a window is no longer in active use by any screen or host view.

Bug: 532112145
Test: StatusBarTest
Relnote: "Added multi-window status bar orchestration support to Wear Compose Material3 scaffolds, allowing dialogs and separate windows to drive their own system status bar controllers."
Change-Id: Ibf82c9b9ee2688c4be81a3e7d90feff446ad7857