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/overworld/overworld_editor.cc

@@ -706,7 +706,7 @@ void OverworldEditor::DrawTile8Selector() {
   graphics_bin_canvas_.DrawContextMenu();
   if (all_gfx_loaded_) {
     int key = 0;
-    for (auto &value : rom_.gfx_sheets()) {
+    for (auto &value : GraphicsSheetManager::GetInstance().gfx_sheets()) {
       int offset = 0x40 * (key + 1);
       int top_left_y = graphics_bin_canvas_.zero_point().y + 2;
       if (key >= 1) {
@@ -1077,9 +1077,15 @@ absl::Status OverworldEditor::LoadGraphics() {
   for (int i = 0; i < zelda3::kNumOverworldMaps; ++i) {
     overworld_.set_current_map(i);
     auto palette = overworld_.current_area_palette();
-    RETURN_IF_ERROR(Renderer::GetInstance().CreateAndRenderBitmap(
-        kOverworldMapSize, kOverworldMapSize, 0x200,
+    try {
+      RETURN_IF_ERROR(Renderer::GetInstance().CreateAndRenderBitmap(
+        kOverworldMapSize, kOverworldMapSize, 0x80,
         overworld_.current_map_bitmap_data(), maps_bmp_[i], palette));
+    }
+    catch (const std::bad_alloc& e) {
+			std::cout << "Error: " << e.what() << std::endl;
+      continue;
+    }
   }
 
   if (core::ExperimentFlags::get().overworld.kDrawOverworldSprites) {

src/app/editor/overworld/overworld_editor.h

@@ -252,7 +252,7 @@ class OverworldEditor : public Editor, public gfx::GfxContext {
   gfx::Bitmap current_gfx_bmp_;
   gfx::Bitmap all_gfx_bmp;
 
-  gfx::BitmapTable maps_bmp_;
+  std::array<gfx::Bitmap, zelda3::kNumOverworldMaps> maps_bmp_;
   gfx::BitmapTable current_graphics_set_;
   gfx::BitmapTable sprite_previews_;