Refactor Renderer access and enhance graphics loading functionality

- Replaced instances of Renderer::GetInstance() with Renderer::Get() for consistency across the codebase.
- Updated various rendering methods to streamline bitmap updates and enhance performance.
- Removed unused includes and comments to improve code clarity and maintainability.

src/app/rom.h

@@ -22,7 +22,6 @@
 #include "app/gfx/bitmap.h"
 #include "app/gfx/snes_palette.h"
 #include "app/gfx/snes_tile.h"
-#include "app/snes.h"
 #include "util/macro.h"
 
 namespace yaze {