orderBy method
Get a list of documents from the collection as a list ordered by the orderBy
limit: optionally provide a maximum value of items to be returned
throws a MissingValueException when no orderBys are given
Implementation
@override
Future<List<T>> orderBy(List<OrderBy> orderBy, {int? limit}) async {
if (orderBy.isEmpty) throw MissingValueException(OrderBy);
final query = ref.sort(orderBy).limitIfNotNull(limit);
final snapshot = await query.get();
return snapshot.docs.toListT();
}