PluralTranslatableMarkup::DELIMITER deprecated in favour of Drupal\Component\Gettext\PoItem::DELIMITER

The constant \Drupal\Core\StringTranslation\PluralTranslatableMarkup::DELIMITER used for splitting plural strings.
As this functionality used in low level component it is defined there now \Drupal\Component\Gettext\PoItem::DELIMITER

All code using PluralTranslatableMarkup::DELIMITER or LOCALE_PLURAL_DELIMITER should use constant \Drupal\Component\Gettext\PoItem::DELIMITER

Before

if (strpos($value, PluralTranslatableMarkup::DELIMITER) !== FALSE) {
 // Process plural string.
}

After

if (strpos($value, PoItem::DELIMITER) !== FALSE) {
 // Process plural string.
}