feat: set close button visibility from option.

src/Ursa/Controls/Dialog/Dialog.cs

@@ -196,6 +196,7 @@ public static class Dialog
         }
         window.WindowStartupLocation = options.StartupLocation;
         window.Title = options.Title;
+        window.IsCloseButtonVisible = options.IsCloseButtonVisible;
         if (options.StartupLocation == WindowStartupLocation.Manual)
         {
             if (options.Position is not null)

src/Ursa/Controls/Dialog/OverlayDialog.cs

@@ -190,6 +190,7 @@ public static class OverlayDialog
         control.VerticalOffset =
             options.VerticalAnchor == VerticalPosition.Center ? null : options.VerticalOffset;
         control.CanClickOnMaskToClose = options.CanClickOnMaskToClose;
+        control.IsCloseButtonVisible = options.IsCloseButtonVisible;
     }
     
     private static void ConfigureDefaultDialogControl(DefaultDialogControl control, OverlayDialogOptions? options)