Add tests to ensure states are properly preserved between unmaps and remaps

[tarek-y-ismail]

Follow up of canonical/mir#4694

Adds a bunch of tests to make sure SurfaceStateTracker properly preserves surface states when surfaces are unmapped and then remapped.

[Copilot]

Pull request overview

This pull request adds comprehensive test coverage to verify that the SurfaceStateTracker in Mir properly preserves window states (restored, maximized, fullscreen) when surfaces are unmapped and then remapped. This is a follow-up to PR #4694 which fixed a bug where windows would incorrectly revert to the restored state after unmap/remap cycles.

Changes:

• Added five new test cases covering different state preservation scenarios during unmap/remap cycles
• Tests verify that restored, maximized, fullscreen, and combined states are maintained
• Includes a test for multiple consecutive unmap/remap cycles

[github-actions]

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[AlanGriffiths]

WLCS is not about testing details of Mir's current implementation. It is about testing the conformance of any Wayland compositor.

Adds a bunch of tests to make sure SurfaceStateTracker properly preserves surface states when surfaces are unmapped and then remapped.

These tests may or may not be valid (I haven't looked), but this description is about a detail of Mir's implementation. Please rephrase to describe behaviour(s) mandated by Wayland

[tarek-y-ismail]

Putting this aside for now until we settle on canonical/mir#4694