Saves a menu link.
After calling this function, rebuild the menu cache using menu_cache_clear_all().
\Drupal\menu_link\Plugin\Core\Entity\MenuLink $menu_link: The menu link entity to be saved.
int|bool Returns SAVED_NEW or SAVED_UPDATED if the save operation succeeded, or FALSE if it failed.
function menu_link_save(MenuLink $menu_link) {
return $menu_link
->save();
}