Appends a translation system to the translation chain.
\Drupal\Core\Translation\Translator\TranslatorInterface $translator: The translation interface to be appended to the translation chain.
int $priority: The priority of the logger being added.
\Drupal\Core\Translation\TranslationManager The called object.
public function addTranslator(TranslatorInterface $translator, $priority = 0) {
$this->translators[$priority][] = $translator;
// Reset sorted translators property to trigger rebuild.
$this->sortedTranslators = NULL;
return $this;
}