feat: Integrate ProjectFileEditor into EditorManager for enhanced project file handling

- Initialized ProjectFileEditor within EditorManager to facilitate project file editing.
- Added menu options for editing project files, including loading and error handling with toast notifications.
- Updated the DrawMenuBar method to render the ProjectFileEditor interface.
- Included necessary header for ProjectFileEditor in editor_manager.h.

src/app/editor/editor_library.cmake

@@ -20,6 +20,7 @@ set(
   app/editor/message/message_data.cc
   app/editor/message/message_preview.cc
   app/editor/code/assembly_editor.cc
+  app/editor/code/project_file_editor.cc
   app/editor/graphics/screen_editor.cc
   app/editor/graphics/graphics_editor.cc
   app/editor/graphics/palette_editor.cc