**Describe the solution you'd like**

An option to make the `IDENTIFIED WITH` section mandatory.

{
        if (!has_user_directories)
            users_config_path = config_path;
    }
    else if (std::filesystem::path{users_config_path}.is_relative() && std::filesystem::exists(config_dir + users_config_path))
        users_config_path = config_dir + users_config_path;
    if (!users_config_path.empty())
    {
        if (users_config_path != config_path)
            checkForUsersNotInMainConfig(config, config_path, users_config_path, getLogger());
        addUsersConfigStorage(
            UsersConfigAccessStorage::STORAGE_TYPE,
            users_config_path,
            include_from_path,
            dbms_dir,
            get_zookeeper_function,
             false);
    }
    String disk_storage_dir = config.getString("access_control_path", "");
    if (!disk_storage_dir.empty())
        addDiskStorage(DiskAccessStorage::STORAGE_TYPE, disk_storage_dir,  false,  true);
    if (has_user_directories)
        addStoragesFromUserDirectoriesConfig(config, "user_directories", config_dir, dbms_dir, include_from_path, get_zookeeper_function);
}
void AccessControl::reload(ReloadMode reload_mode)
{
    MultipleAccessStorage::reload(reload_mode);
    changes_notifier->sendNotifications();
}
scope_guard AccessControl::subscribeForChanges(AccessEntityType type, const OnChangedHandler & handler) const