Refactor DungeonEditor and related components for improved object management and UI enhancements

- Replaced vertical separators with standard separators in the EditorManager's menu bar for consistency.
- Introduced a new room selection callback mechanism in DungeonRoomSelector to facilitate room selection events.
- Enhanced DungeonEditor with drag-and-select functionality for object placement, improving user interaction.
- Added an object browser in DungeonObjectSelector for better object management and preview capabilities.
- Streamlined object rendering and selection processes, ensuring a more intuitive editing experience.

src/app/editor/overworld/overworld_editor.cc

@@ -2505,7 +2505,7 @@ absl::Status OverworldEditor::UpdateUsageStats() {
       for (int i = 0; i < 0x81; i++) {
         auto entrance_name = rom_->resource_label()->CreateOrGetLabel(
             "Dungeon Entrance Names", util::HexByte(i),
-            zelda3::kEntranceNames[i].data());
+            zelda3::kEntranceNames[i]);
         std::string str = absl::StrFormat("%#x - %s", i, entrance_name);
         if (Selectable(str.c_str(), selected_entrance_ == i,
                        overworld_.entrances().at(i).deleted