优化更新代码，添加界面功能并整合

WPFluent/Controls/NavigationView/NavigationViewItemHeader.cs

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+
+
+
+// Based on Windows UI Library
+// Copyright(c) Microsoft Corporation.All rights reserved.
+//
+// https://docs.microsoft.com/en-us/uwp/api/windows.ui.xaml.controls.navigationviewitemheader?view=winrt-22621
+
+// ReSharper disable once CheckNamespace
+
+namespace WPFluent.Controls;
+
+/// <summary>
+/// Represents a header for a group of menu items in a NavigationMenu.
+/// </summary>
+public class NavigationViewItemHeader : System.Windows.Controls.Control
+{
+    /// <summary>
+    /// Identifies the <see cref="Icon"/> dependency property.
+    /// </summary>
+    public static readonly DependencyProperty IconProperty = DependencyProperty.Register(
+        nameof(Icon),
+        typeof(IconElement),
+        typeof(NavigationViewItemHeader),
+        new PropertyMetadata(null));
+    /// <summary>
+    /// Identifies the <see cref="Text"/> dependency property.
+    /// </summary>
+    public static readonly DependencyProperty TextProperty = DependencyProperty.Register(
+        nameof(Text),
+        typeof(string),
+        typeof(NavigationViewItemHeader),
+        new PropertyMetadata(string.Empty));
+
+    /// <summary>
+    /// Gets or sets the icon.
+    /// </summary>
+    [Bindable(true)]
+    [Category("Appearance")]
+    public IconElement? Icon { get => (IconElement?)GetValue(IconProperty); set => SetValue(IconProperty, value); }
+
+    /// <summary>
+    /// Gets or sets the text presented in the header element.
+    /// </summary>
+    [Bindable(true)]
+    public string Text { get => (string)GetValue(TextProperty); set => SetValue(TextProperty, value); }
+}