Access callback for the translation overview page.
\Drupal\Core\Entity\EntityInterface $entity: The entity whose translation overview should be displayed.
function translation_entity_translate_access(EntityInterface $entity) {
$entity_type = $entity
->entityType();
return empty($entity
->language()->locked) && language_multilingual() && $entity
->isTranslatable() && (user_access('create entity translations') || user_access('update entity translations') || user_access('delete entity translations'));
}