chore: rename demo files.

src/Shared/HandyControlDemo_Shared/UserControl/Controls/ImageSelectorDemo.xaml.cs

@@ -0,0 +1,9 @@
+namespace HandyControlDemo.UserControl;
+
+public partial class ImageSelectorDemoCtl
+{
+    public ImageSelectorDemoCtl()
+    {
+        InitializeComponent();
+    }
+}