refactor: Update window creation and file dialog handling for improved consistency

- Replaced `SDL_Deleter` with `util::SDL_Deleter` in window creation for better utility usage.
- Updated file dialog methods to consistently reference `core::FeatureFlags` for feature flag checks.
- Refactored file extension retrieval in `EditorManager` to use `util::GetFileExtension` for consistency.
- Adjusted `MusicEditor` constructor to accept a ROM pointer, enhancing initialization clarity.
- Commented out unused code in `MusicEditor` to improve readability and maintainability.
- Updated include paths in `overworld_editor.cc` for better organization.
- Cleaned up commented-out code in `editor_selection_dialog.cc` and `welcome_screen.cc` for clarity.

src/app/editor/editor_manager.h

@@ -48,7 +48,7 @@ class EditorSet {
       : assembly_editor_(rom),
         dungeon_editor_(rom),
         graphics_editor_(rom),
-        music_editor_(),
+        music_editor_(rom),
         overworld_editor_(rom),
         palette_editor_(rom),
         screen_editor_(rom),