Refactor project structure and enhance functionality

Changed the project namespace from `Ghost.Editor` to `Ghost.App` across multiple files.
Changed the `InternalsVisibleTo` attribute in `AssemblyInfo.cs` to include `Ghost.App`.
Changed the `ProjectRepository` class to add new asynchronous methods for retrieving projects by ID, name, and metadata path.
Changed the `ProjectService` class to utilize the new asynchronous project loading methods.
Changed the `SceneGraph` classes to improve node management and serialization.
Changed the `EntityManager` class to enhance entity management with new component handling methods.
Added new test classes, `EntityTest` and `SerializationTest`, to ensure reliability in entity and serialization systems.
Added the `Ghost.App` project file to establish a modular project structure.
Added the `Ghost.Generator` project for automated component serialization code generation.
Updated UI components to reflect the new namespace for proper functionality.

Ghost.Editor/View/Windows/EngineEditorWindow.xaml.cs

@@ -1,37 +0,0 @@
-using Ghost.Data.Resources;
-using Ghost.Editor.ViewModels.Windows;
-using Ghost.Engine.Resources;
-using WinUIEx;
-
-// To learn more about WinUI, the WinUI project structure,
-// and more about our project templates, see: http://aka.ms/winui-project-info.
-
-namespace Ghost.Editor.View.Windows;
-/// <summary>
-/// An empty window that can be used on its own or navigated to within a Frame.
-/// </summary>
-internal sealed partial class EngineEditorWindow : WindowEx
-{
-    public EngineEditorViewModel ViewModel
-    {
-        get;
-    }
-
-    public EngineEditorWindow()
-    {
-        ViewModel = App.GetService<EngineEditorViewModel>();
-
-        AppWindow.SetIcon(AssetsPath.s_appIconPath);
-        Title = EngineData.ENGINE_NAME;
-        ExtendsContentIntoTitleBar = true;
-
-        InitializeComponent();
-
-        this.CenterOnScreen();
-    }
-
-    private void WindowEx_Activated(object sender, Microsoft.UI.Xaml.WindowActivatedEventArgs args)
-    {
-        Bindings.Update();
-    }
-}