优化更新代码，添加界面功能并整合

WPFluent/Controls/MessageBox/MessageBoxButtonClickDeferral.cs

@@ -0,0 +1,18 @@
+using System;
+
+namespace WPFluent.Controls;
+
+public sealed class MessageBoxButtonClickDeferral
+{
+    private readonly Action _handler;
+
+    internal MessageBoxButtonClickDeferral(Action handler)
+    {
+        _handler = handler ?? throw new ArgumentNullException(nameof(handler));
+    }
+
+    public void Complete()
+    {
+        _handler();
+    }
+}