feat: Add tests for Wolf3dGuiApp and refactor game data picker management

- Introduced unit tests for the Wolf3dGuiApp to ensure proper directory configuration and audio management.
- Refactored the GameDataPickerManager to streamline directory and file selection processes.
- Removed obsolete GameDataPickerManager and Wolf3dAppManager classes to simplify the architecture.
- Enhanced the Wolf3dFlutterEngine to improve game version handling during save loading.
- Updated existing tests to reflect changes in the game data management structure.
- Removed unnecessary dependencies and cleaned up the codebase for better maintainability.

Signed-off-by: Hans Kokx <hans.d.kokx@gmail.com>

apps/wolf_3d_gui/lib/main.dart

@@ -2,6 +2,8 @@ import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:wolf_3d_flutter/wolf_3d_flutter.dart';
 
+import 'wolf3d_gui_app.dart';
+
 /// Creates the application shell after loading available Wolf3D data sets.
 void main() async {
   WidgetsFlutterBinding.ensureInitialized();
@@ -12,7 +14,7 @@ void main() async {
 
   runApp(
     MaterialApp(
-      home: Wolf3dApp(engine: wolf3d),
+      home: Wolf3dGuiApp(engine: wolf3d),
     ),
   );
 }