On Wayland hiding a window requires destroying the surface, which
means destroying the winit window as well as the underlying graphics
surface. The latter is tricky as we have to keep the renderer around,
as our WindowAdapter trait's `renderer()` function returns a `&dyn
Renderer` and that also has to work without a window (to obtain text
metrics).
Fixes#4225
Co-Authored-By: Olivier Goffart <olivier.goffart@slint.dev>