Enhance tilemap functionality and improve bitmap handling

- Replaced instances of Renderer::GetInstance() with Renderer::Get() for consistency in tilemap rendering.
- Introduced new functions for fetching and mirroring tile data, enhancing tile manipulation capabilities.
- Added ComposeTile16 function to facilitate the composition of 16x16 tile graphics from individual tile parts.
- Updated RenderTile to handle bitmap updates more efficiently and ensure proper rendering of tiles.
- Included necessary header for SNES tile handling to support new functionalities.

src/app/gfx/tilemap.h

@@ -2,6 +2,7 @@
 #define YAZE_GFX_TILEMAP_H
 
 #include "app/gfx/bitmap.h"
+#include "app/gfx/snes_tile.h"
 #include "absl/container/flat_hash_map.h"
 
 namespace yaze {
@@ -26,6 +27,11 @@ void UpdateTilemap(Tilemap &tilemap, const std::vector<uint8_t> &data);
 
 void RenderTile(Tilemap &tilemap, int tile_id);
 
+void ComposeTile16(Tilemap &tilemap, const std::vector<uint8_t> &data,
+                   const TileInfo &top_left, const TileInfo &top_right,
+                   const TileInfo &bottom_left, const TileInfo &bottom_right,
+                   int sheet_offset);
+
 std::vector<uint8_t> GetTilemapData(Tilemap &tilemap, int tile_id);
 
 }  // namespace gfx