优化更新代码，添加界面功能并整合

WPFluent/Controls/ContentDialog/ContentDialogClosedEventArgs.cs

@@ -0,0 +1,15 @@
+// This Source Code Form is subject to the terms of the MIT License.
+// If a copy of the MIT was not distributed with this file, You can obtain one at https://opensource.org/licenses/MIT.
+// Copyright (C) Leszek Pomianowski and WPF UI Contributors.
+// All Rights Reserved.
+
+// ReSharper disable once CheckNamespace
+namespace WPFluent.Controls;
+
+public class ContentDialogClosedEventArgs : RoutedEventArgs
+{
+    public ContentDialogClosedEventArgs(RoutedEvent routedEvent, object source)
+        : base(routedEvent, source) { }
+
+    public required ContentDialogResult Result { get; init; }
+}