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/Core/SceneGraph/EditorWorldManager.cs

@@ -0,0 +1,53 @@
+using Ghost.Editor.Resources;
+using Ghost.Editor.Services.Contracts;
+using Ghost.Engine.Resources;
+using System.Text.Json;
+
+namespace Ghost.Editor.Core.SceneGraph;
+
+public enum OpenWorldMode
+{
+    Single,
+    Additive,
+    AdditiveWithoutLoading
+}
+
+public static class EditorWorldManager
+{
+    // TODO: Use guid keys instead of string paths for better performance and uniqueness
+    private static readonly Dictionary<string, WorldNode> _loadedWorlds = new();
+    public static IEnumerable<WorldNode> LoadedWorlds => _loadedWorlds.Values;
+
+    public static event Action<WorldNode>? OnWorldLoaded;
+    public static event Action<WorldNode>? OnWorldUnloaded;
+
+    public static async Task LoadWorld(string worldPath)
+    {
+        if (_loadedWorlds.ContainsKey(worldPath)
+            || !File.Exists(worldPath)
+            || Path.GetExtension(worldPath) != FileExtensions.SCENE_FILE_EXTENSION)
+        {
+            return;
+        }
+
+        var progressService = EditorApplication.GetService<IProgressService>();
+        progressService.ShowIndeterminateProgress("Loading world...");
+
+        foreach (var world in _loadedWorlds)
+        {
+            world.Value.Unload();
+            OnWorldUnloaded?.Invoke(world.Value);
+        }
+
+        await using var readStream = new FileStream(worldPath, FileMode.Open, FileAccess.Read, FileShare.Read);
+        var deserializedScene = await JsonSerializer.DeserializeAsync<WorldNode>(readStream, StaticResource.defaultSerializerOptions) ?? throw new Exception("Deserialization failed.");
+
+        _loadedWorlds.Clear();
+
+        _loadedWorlds[worldPath] = deserializedScene;
+        await deserializedScene.LoadAsync();
+
+        progressService.HideProgress();
+        OnWorldLoaded?.Invoke(deserializedScene);
+    }
+}