Force rounded corners

[es183923]

In windows 11, apps can opt in to have rounded corners, which match the UI better.

References: https://docs.microsoft.com/en-us/windows/apps/desktop/modernize/apply-rounded-corners https://docs.microsoft.com/en-us/windows/win32/api/dwmapi/ne-dwmapi-dwm_window_corner_preference

Check out MicaForEveryone, which also implements this: https://github.com/MicaForEveryone/MicaForEveryone/blob/2e46914c955ed694a1edee7eac97d4a6eb98cb40/MicaForEveryone.Win32/DesktopWindowManager.cs#L99-L107