[Windows] Hide/show titlebar on modal pages

[Foda]

Description of Change

Toggle the titlebar visibility when modal pages are pushed/popped.

Issues Fixed

Fixes #25964

[PureWeen]

/backport to release/9.0.1xx

[github-actions]

Started backporting to release/9.0.1xx: https://github.com/dotnet/maui/actions/runs/11981567160

[mattleibow]

Can we get tests for this one?

[PureWeen]

Can we get tests for this one?

we could probably validate the raw control.
The screen shot tests don't work because we cut off the titlebar so we can use screen comparison tests :-/

We're going to add a manual test as well here for validation

[jsuarezruiz]

Can we get tests for this one?

Can we get tests for this one?

we could probably validate the raw control. The screen shot tests don't work because we cut off the titlebar so we can use screen comparison tests :-/

We're going to add a manual test as well here for validation

We could maybe manage the cutting logic, to avoid it when necessary. But, yeah, with a Device Test should be enough.

[jsuarezruiz]

Could include a device test? https://github.com/dotnet/maui/tree/main/src/Controls/tests/DeviceTests

[Foda]

Sure -- lemme add that to the existing modal push/pop Windows tests