添加treeview手动清空缓存方法，因为如果组件一直存在，而items不断增删更新的话，缓存不会释放

Author: kimdiego2098

src/BootstrapBlazor/Components/TreeView/TreeView.razor.cs

@@ -303,6 +303,14 @@ protected override void OnInitialized()
         ToolbarEditLabelText ??= Localizer[nameof(ToolbarEditLabelText)];
     }
 
+    /// <summary>
+    /// Clear the cache of the tree node state.
+    /// </summary>
+    public void ClearCache()
+    {
+        _treeNodeStateCache?.Reset();
+    }
+
     /// <summary>
     /// <inheritdoc/>
     /// </summary>