优化更新代码，添加界面功能并整合

WPFluent/Controls/CardExpander/CardExpander.cs

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+
+
+
+// ReSharper disable once CheckNamespace
+namespace WPFluent.Controls;
+
+/// <summary>
+/// Inherited from the <see cref="System.Windows.Controls.Expander"/> control which can hide the collapsible content.
+/// </summary>
+public class CardExpander : System.Windows.Controls.Expander
+{
+    /// <summary>
+    /// Identifies the <see cref="ContentPadding"/> dependency property.
+    /// </summary>
+    public static readonly DependencyProperty ContentPaddingProperty = DependencyProperty.Register(
+        nameof(ContentPadding),
+        typeof(Thickness),
+        typeof(CardExpander),
+        new FrameworkPropertyMetadata(default(Thickness), FrameworkPropertyMetadataOptions.AffectsParentMeasure));
+
+    /// <summary>
+    /// Identifies the <see cref="CornerRadius"/> dependency property.
+    /// </summary>
+    public static readonly DependencyProperty CornerRadiusProperty = DependencyProperty.Register(
+        nameof(CornerRadius),
+        typeof(CornerRadius),
+        typeof(CardExpander),
+        new PropertyMetadata(new CornerRadius(4)));
+    /// <summary>
+    /// Identifies the <see cref="Icon"/> dependency property.
+    /// </summary>
+    public static readonly DependencyProperty IconProperty = DependencyProperty.Register(
+        nameof(Icon),
+        typeof(IconElement),
+        typeof(CardExpander),
+        new PropertyMetadata(null, null, IconElement.Coerce));
+
+    /// <summary>
+    /// Gets or sets content padding Property
+    /// </summary>
+    [Bindable(true)]
+    [Category("Layout")]
+    public Thickness ContentPadding
+    {
+        get { return (Thickness)GetValue(ContentPaddingProperty); }
+        set { SetValue(ContentPaddingProperty, value); }
+    }
+
+    /// <summary>
+    /// Gets or sets displayed <see cref="IconElement"/>.
+    /// </summary>
+    [Bindable(true)]
+    [Category("Appearance")]
+    public CornerRadius CornerRadius
+    {
+        get => (CornerRadius)GetValue(CornerRadiusProperty);
+        set => SetValue(CornerRadiusProperty, value);
+    }
+
+    /// <summary>
+    /// Gets or sets displayed <see cref="IconElement"/>.
+    /// </summary>
+    [Bindable(true)]
+    [Category("Appearance")]
+    public IconElement? Icon { get => (IconElement?)GetValue(IconProperty); set => SetValue(IconProperty, value); }
+}