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.InternalEditor/Utilities/SystemUtilities.cs

@@ -0,0 +1,42 @@
+using System;
+using System.Collections.Generic;
+using System.Threading.Tasks;
+using Windows.Storage;
+using Windows.Storage.Pickers;
+using WinRT.Interop;
+
+namespace Ghost.App.Utilities;
+
+public static class SystemUtilities
+{
+    public static async Task<StorageFolder?> OpenFolderPickerAsync(PickerLocationId startLocation = PickerLocationId.DocumentsLibrary, string settingsIdentifier = "")
+    {
+        var openPicker = new FolderPicker();
+        var hWnd = WindowNative.GetWindowHandle(GhostApplication.Window);
+        InitializeWithWindow.Initialize(openPicker, hWnd);
+
+        openPicker.SuggestedStartLocation = startLocation;
+        openPicker.FileTypeFilter.Add("*");
+        openPicker.SettingsIdentifier = settingsIdentifier;
+
+        var folder = await openPicker.PickSingleFolderAsync();
+        return folder;
+    }
+
+    public static async Task<StorageFile?> OpenFilePickerAsync(PickerLocationId startLocation = PickerLocationId.DocumentsLibrary, string settingsIdentifier = "", params IEnumerable<string> filter)
+    {
+        var openPicker = new FileOpenPicker();
+        var hWnd = WindowNative.GetWindowHandle(GhostApplication.Window);
+        InitializeWithWindow.Initialize(openPicker, hWnd);
+
+        openPicker.SuggestedStartLocation = startLocation;
+        openPicker.SettingsIdentifier = settingsIdentifier;
+        foreach (var fileType in filter)
+        {
+            openPicker.FileTypeFilter.Add(fileType);
+        }
+
+        var file = await openPicker.PickSingleFileAsync();
+        return file;
+    }
+}