Validate the segments from the JobItemForm.
If the form does not validate, it will add the error to the $element.
\Drupal\Core\Form\FormStateInterface $form_state: A string with the XML serialized data.
array $element: The translation element of the form.
\Drupal\tmgmt\JobItemInterface $job_item: The Job Item.
public function validateFormTranslation(FormStateInterface &$form_state, $element, JobItemInterface $job_item);