Refactor graphics sheet management with singleton class

Refactor the handling of graphics sheets by introducing a singleton class `GraphicsSheetManager`. This centralizes the management of graphics sheets, replacing direct access through the `Rom` object. Key changes include:

- Updated various methods across multiple classes to use `GraphicsSheetManager::GetInstance()` for accessing and manipulating graphics sheets.
- Introduced standalone functions `LoadLinkGraphics`, `LoadAllGraphicsData`, and `SaveAllGraphicsData` for loading and saving graphics data.
- Refactored the `Rom` class to remove methods and member variables related to graphics sheet management.
- Updated `OverworldEditor` to use `std::array` for `maps_bmp_` and added error handling for `std::bad_alloc` exceptions.
- Improved code modularity and error handling throughout the application.

src/app/editor/sprite/sprite_editor.cc

@@ -175,7 +175,7 @@ void SpriteEditor::DrawCurrentSheets() {
     graphics_sheet_canvas_.DrawTileSelector(32);
     for (int i = 0; i < 8; i++) {
       graphics_sheet_canvas_.DrawBitmap(
-          rom()->gfx_sheets().at(current_sheets_[i]), 1, (i * 0x40) + 1, 2);
+          GraphicsSheetManager::GetInstance().gfx_sheets().at(current_sheets_[i]), 1, (i * 0x40) + 1, 2);
     }
     graphics_sheet_canvas_.DrawGrid();
     graphics_sheet_canvas_.DrawOverlay();