replace v6 with experimental v7 code

src/MpvNet.Windows/WPF/MsgBox/MsgBoxUrl.cs

@@ -0,0 +1,13 @@
+
+using System.Windows.Media;
+
+namespace MpvNet.Windows.WPF.MsgBox;
+
+public class MsgBoxUrl
+{
+    public Uri? URL { get; set; }
+    public string? DisplayName { get; set; }
+    public Color Foreground { get; set; }
+
+    public MsgBoxUrl() => Foreground = MessageBoxEx.DefaultUrlForegroundColor;
+}