Refactor project from Ghost.App to Ghost.Editor

Changed the project structure to reflect a shift from `Ghost.App` to `Ghost.Editor`, updating namespaces and class names throughout.

Changed the application class in `App.xaml` and `App.xaml.cs` from `GhostApplication` to `EditorApplication`.

Changed several service interfaces to reside under `Ghost.Editor.Services.Contracts`, including `IInspectorService`, `INotificationService`, and `IProgressService`.

Added `InspectorView` and `InspectorViewModel` classes to manage inspector functionality.

Added `NavigationTabView` and `NavigationTabPage` classes to facilitate navigation within the editor.

Enhanced `WorldNode` and `EntityNode` classes to support scene graph functionality, including serialization and entity management.

Updated the project file `Ghost.Editor.csproj` to reflect the new structure and removed old references.

Modified the solution file `GhostEngine.sln` to remove references to `Ghost.App` and include `Ghost.Editor`.

Updated unit tests to align with the new namespaces and project structure.

Ghost.App/Controls/Internal/NavigationTabView.cs

@@ -0,0 +1,39 @@
+using Ghost.Editor.Contracts;
+using Microsoft.UI.Xaml.Controls;
+
+namespace Ghost.Editor.Controls.Internal;
+
+public partial class NavigationTabPage : TabViewItem, INavigationAware
+{
+    public virtual void OnNavigatedTo(object? parameter)
+    {
+    }
+
+    public virtual void OnNavigatedFrom()
+    {
+    }
+}
+
+public sealed partial class NavigationTabView : TabView
+{
+    public NavigationTabView()
+    {
+        this.SelectionChanged += NavigationTabView_SelectionChanged;
+    }
+
+    private void NavigationTabView_SelectionChanged(object sender, SelectionChangedEventArgs e)
+    {
+        foreach (var oldItem in e.RemovedItems)
+        {
+            if (oldItem is NavigationTabPage oldPage)
+            {
+                oldPage.OnNavigatedFrom();
+            }
+        }
+
+        if (SelectedItem is NavigationTabPage newPage)
+        {
+            newPage.OnNavigatedTo(null);
+        }
+    }
+}