优化更新代码，添加界面功能并整合

WPFluent/Controls/NavigationView/NavigationViewBackButtonVisible.cs

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+
+
+
+// Based on Windows UI Library
+// Copyright(c) Microsoft Corporation.All rights reserved.
+
+// ReSharper disable once CheckNamespace
+namespace WPFluent.Controls;
+
+/// <summary>
+/// Defines constants that specify whether the back button is visible in NavigationView.
+/// </summary>
+public enum NavigationViewBackButtonVisible
+{
+    /// <summary>
+    /// Do not display the back button in NavigationView, and do not reserve space for it in layout.
+    /// </summary>
+    Collapsed,
+
+    /// <summary>
+    /// Display the back button in NavigationView.
+    /// </summary>
+    Visible,
+
+    /// <summary>
+    /// The system chooses whether or not to display the back button, depending on the device/form factor. On phones,
+    /// tablets, desktops, and hubs, the back button is visible. On Xbox/TV, the back button is collapsed.
+    /// </summary>
+    Auto,
+}