Refactor application structure and add unit tests

Added:
- New `ProgressService` class for managing progress indicators.
- New `AssetDatabase`, `AssetOpenHandlerAttribute`, and `AsyncAssetOpenHandlerAttribute` classes for asset handling.
- `Ghost.UnitTest` project for unit testing with associated files and configurations.

Changed:
- `ActivationHandler` class to ensure correct handling of `LaunchActivatedEventArgs`.
- `App.xaml.cs` to register `INotificationService` and `IProgressService`, replacing `StackedNotificationService`.
- `OnLaunched` method in `App.xaml.cs` to correctly call `ActivationHandler.Handle(args)` and start the host.
- `INavigationAware` interface from internal to public for broader access.
- `EditorState.cs` to activate `EditorApplication` with the current service provider.
- Property names in `AssetItem` and `ExplorerItem` structs to `Name` and `FullName`.
- `NotificationService` class to implement `INotificationService` and refactor notification handling.
- `AssetPathToGlyphConverter` to handle file extensions consistently.
- Bindings in `ProjectPage.xaml` and `ProjectPage.xaml.cs` to use `FullName` instead of `Path`.
- `EngineEditorWindow` and `LandingWindow` classes to utilize new notification and progress services.
- `Logger` class to include a new method for logging errors with exceptions.

Updated:
- Manifest files and project files to reflect new structure and dependencies.
- Solution file `GhostEngine.sln` to include the new unit test project.
- Added several new test classes and methods in `UnitTests.cs`.

Ghost.App/View/Windows/LandingWindow.xaml.cs

@@ -0,0 +1,66 @@
+using Ghost.App.Services;
+using Ghost.App.View.Pages.Landing;
+using Ghost.Data.Resources;
+using Ghost.Editor.Services.Contracts;
+using Ghost.Engine.Resources;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.UI.Xaml.Controls;
+using Microsoft.UI.Xaml.Media.Animation;
+using WinUIEx;
+
+namespace Ghost.App.View.Windows;
+
+internal sealed partial class LandingWindow : WindowEx
+{
+    private IServiceScope? _landingScope;
+
+    private readonly NotificationService _notificationService;
+
+    private int _previousSelectedIndex;
+
+    public LandingWindow()
+    {
+        _notificationService = (NotificationService)GhostApplication.GetService<INotificationService>();
+
+        AppWindow.SetIcon(AssetsPath.s_appIconPath);
+        Title = EngineData.ENGINE_NAME;
+
+        InitializeComponent();
+
+        this.SetWindowSize(1000, 750);
+        this.CenterOnScreen();
+
+        ExtendsContentIntoTitleBar = true;
+    }
+
+    private void WindowEx_Activated(object sender, Microsoft.UI.Xaml.WindowActivatedEventArgs args)
+    {
+        _landingScope?.Dispose();
+        _landingScope = GhostApplication.CreateScope();
+        _notificationService.SetReference(InfoBar, NotificationQueue);
+    }
+
+    private void WindowEx_Closed(object sender, Microsoft.UI.Xaml.WindowEventArgs args)
+    {
+        _landingScope?.Dispose();
+        _notificationService.ClearReference();
+    }
+
+    private void SelectorBar_SelectionChanged(SelectorBar sender, SelectorBarSelectionChangedEventArgs e)
+    {
+        var selectedItem = sender.SelectedItem;
+        var currentSelectedIndex = sender.Items.IndexOf(selectedItem);
+        var pageType = currentSelectedIndex switch
+        {
+            1 => typeof(CreateProjectPage),
+            _ => typeof(OpenProjectPage),
+        };
+
+        var slideNavigationTransitionEffect = currentSelectedIndex - _previousSelectedIndex > 0 ?
+            SlideNavigationTransitionEffect.FromRight : SlideNavigationTransitionEffect.FromLeft;
+
+        ContentFrame.Navigate(pageType, _landingScope, new SlideNavigationTransitionInfo() { Effect = slideNavigationTransitionEffect });
+
+        _previousSelectedIndex = currentSelectedIndex;
+    }
+}