Sorts by an aggregated value.
string $field: The name of a field.
string $function: The aggregate function. This is only marked optional for interface compatibility, it is illegal to leave it out.
string $direction: The order of sorting, either DESC for descending of ASC for ascending.
string $langcode: (optional) The language code.
\Drupal\Core\Entity\Query\QueryAggregateInterface The called object.
public function sortAggregate($field, $function, $direction = 'ASC', $langcode = NULL);