restructure project for part 2

Hyperbar.Controls.Windows/DesktopBar/DesktopBarPresenter.cs

@@ -0,0 +1,40 @@
+using Microsoft.UI.Xaml;
+using Microsoft.UI.Xaml.Controls;
+using Microsoft.UI.Xaml.Data;
+
+namespace Hyperbar.Controls.Windows;
+
+public class DesktopBarPresenter :
+    ContentControl
+{
+    public static readonly DependencyProperty TemplateSettingsProperty =
+        DependencyProperty.Register(nameof(TemplateSettings),
+            typeof(DesktopBarPresenterTemplateSettings), typeof(DesktopBarPresenter),
+            new PropertyMetadata(null));
+
+    internal new DesktopBar? Parent;
+
+    public DesktopBarPresenter()
+    {
+        DefaultStyleKey = typeof(DesktopBarPresenter);
+        TemplateSettings = new DesktopBarPresenterTemplateSettings();
+    }
+
+    protected override void OnApplyTemplate()
+    {
+        SetBinding(ContentProperty, new Binding
+        {
+            Source = Parent,
+            Mode = BindingMode.TwoWay,
+            Path = new PropertyPath(nameof(Parent.Content)),
+        });
+    }
+
+    public DesktopBarPresenterTemplateSettings TemplateSettings
+    {
+        get => (DesktopBarPresenterTemplateSettings)GetValue(TemplateSettingsProperty);
+        set => SetValue(TemplateSettingsProperty, value);
+    }
+
+    internal void UpdatePlacementState(DesktopBarPlacemenet placement) => VisualStateManager.GoToState(this, $"{placement}Placement", true);
+}