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/Converters/AssetPathToGlyphConverter.cs

@@ -0,0 +1,40 @@
+using Microsoft.UI.Xaml.Data;
+using System;
+using System.IO;
+
+namespace Ghost.Editor.Utilities.Converters;
+
+public partial class AssetPathToGlyphConverter : IValueConverter
+{
+    public object? Convert(object value, Type targetType, object parameter, string language)
+    {
+        if (value is not string path)
+        {
+            return null;
+        }
+
+        if (Directory.Exists(path))
+        {
+            return "\uE8B7";
+        }
+
+        var extension = Path.GetExtension(path).ToLowerInvariant();
+
+        // TODO: Use resource dictionary for icons.
+        return extension switch
+        {
+            ".fbx" or ".obj" => "\uF158",
+            ".png" or ".jpg" or ".jpeg" or ".gif" or ".bmp" => "\uE91B", // Image icon
+            ".mp3" or ".wav" or ".ogg" => "\uE767", // Audio icon
+            ".mp4" or ".avi" or ".mkv" => "\uE714", // Video icon
+            ".txt" or ".md" => "\uF000", // Text file icon
+            ".cs" or ".hlsl" => "\uE943", // Code file icon
+            _ => "\uE8A5", // Default file icon
+        };
+    }
+
+    public object ConvertBack(object value, Type targetType, object parameter, string language)
+    {
+        throw new NotImplementedException();
+    }
+}