Implement dungeon map screen drawing functionality in ScreenEditor

- Added DrawDungeonMapScreen method to encapsulate the logic for rendering the dungeon map, improving code organization and readability.
- Refactored DrawDungeonMapsTabs to utilize the new DrawDungeonMapScreen method, reducing code duplication.
- Updated various drawing operations for better clarity and efficiency, including adjustments to tile rendering and grid display.
- Removed commented-out code to clean up the implementation.

src/app/gui/canvas.cc

@@ -111,7 +111,7 @@ void Canvas::DrawContextMenu() {
 
   static bool show_bitmap_data = false;
   if (show_bitmap_data && bitmap_ != nullptr) {
-    MemoryEditor mem_edit;
+    static MemoryEditor mem_edit;
     mem_edit.DrawWindow("Bitmap Data", (void *)bitmap_->data(), bitmap_->size(),
                         0);
   }