PackItem<T>.fromRaw  constructor 
- required SetonixData pack,
- required String namespace,
- required String path,
- required T item,
Implementation
factory PackItem.fromRaw({
  required SetonixData pack,
  required String namespace,
  required String path,
  required T item,
}) =>
    PackItem(item: item, pack: pack, location: ItemLocation(namespace, path));