Adding Unicode support also to D8

In many languages, counting letters does not work correctly.

In the previous Drupal 7 version we used drupal_strlen() function.

if (drupal_strlen($node->title) > $type_max_chars) {
  form_set_error('title', t("Title should not exceed @num characters", array('@num' => $type_max_chars)));
}

Now we need use Drupal\Component\Utility\Unicode::strlen(). It counts the number of characters in a UTF-8 string.

if (Unicode::strlen($value_title) > $config_value) {
  $this->context->addViolation("Title should not exceed $config_value character(s)");
}