[nostalgia/core] Move most TileSheet member functions out of class

src/nostalgia/modules/scene/include/nostalgia/scene/scenestatic.hpp

@@ -42,7 +42,7 @@ struct TileDoc {
 		if (subsheetId > -1) {
 			return subsheetId;
 		}
-		return ts.getIdFor(subsheetPath);
+		return getIdFor(ts, subsheetPath);
 	}
 
 	[[nodiscard]]
@@ -50,7 +50,7 @@ struct TileDoc {
 			core::TileSheet const&ts) const noexcept {
 		// prefer the already present path
 		if (!subsheetPath.len()) {
-			return ts.getNameFor(subsheetId);
+			return core::getNameFor(ts, subsheetId);
 		}
 		return ox::StringView(subsheetPath);
 	}

src/nostalgia/modules/scene/src/keel/typeconv.cpp

@@ -54,7 +54,7 @@ ox::Error SceneDocToSceneStaticConverter::convert(
 				auto dstTile = dstLayer.tile(tileIdx);
 				dstTile.tileType = srcTile.type;
 				oxRequire(path, srcTile.getSubsheetPath(*ts));
-				oxRequire(mapIdx, ts->getTileOffset(path));
+				oxRequire(mapIdx, getTileOffset(*ts, path));
 				dstTile.tileMapIdx = static_cast<uint16_t>(mapIdx);
 				setLayerAttachments(layerIdx, srcTile, dstTile);
 				++tileIdx;