refactor(editor): extract editor management responsibilities into dedicated classes

- Introduced EditorRegistry, ProjectManager, and RomFileManager to streamline editor operations and improve code organization.
- Refactored EditorManager to delegate responsibilities to the new classes, enhancing maintainability and clarity.
- Updated CMake configuration to include new source files for the extracted components.

Benefits:
- Improves separation of concerns within the editor, leading to a more modular and manageable codebase.
- Enhances the overall architecture by clearly defining roles for editor management, project handling, and ROM file operations.

src/app/editor/editor_library.cmake

@@ -33,9 +33,12 @@ set(
   app/editor/sprite/sprite_editor.cc
   app/editor/system/command_manager.cc
   app/editor/system/command_palette.cc
+  app/editor/system/editor_registry.cc
   app/editor/system/extension_manager.cc
   app/editor/system/popup_manager.cc
+  app/editor/system/project_manager.cc
   app/editor/system/proposal_drawer.cc
+  app/editor/system/rom_file_manager.cc
   app/editor/system/session_card_registry.cc
   app/editor/system/settings_editor.cc
   app/editor/system/shortcut_manager.cc