TreeViewItem element updated with new attributes

Updated the `TreeViewItem` element in several ways. The `Content` attribute, previously bound to `DisplayName`, has been removed, meaning the element no longer displays the `DisplayName` as its content. An `IsExpanded` attribute has been added with a default value of `True`, causing the element to always be expanded. Additionally, an `ItemsSource` attribute has been added and bound to `Children`, allowing the element to display child items if any are present.

src/electrifier/Controls/Vanara/Shell32TreeView.xaml

@@ -13,8 +13,7 @@
  ItemsSource="{x:Bind RootShellItems}">
  <TreeView.ItemTemplate>
  <DataTemplate x:DataType="local:Shell32TreeViewItem">
- <TreeViewItem Content="{x:Bind DisplayName}"
- HasUnrealizedChildren="{x:Bind HasUnrealizedChildren}"
+ <TreeViewItem HasUnrealizedChildren="{x:Bind HasUnrealizedChildren}"
  IsExpanded="True"
  ItemsSource="{x:Bind Children}">
  <StackPanel Orientation="Horizontal"