[site-reviews] Use Anonymous if a name is not given

/**
 * Always use "Anonymous" when a name is not given (i.e. do not use the display name of the user)
 *
 * @param array $values
 * @param string $method
 * @param array $args
 * @return array
 */
add_filter('site-reviews/defaults/create-review', function (array $values, $method, $args) {
    if (empty($args['name'])) {
        $values['name'] = 'Anonymous';
    }
    return $values;
}, 10, 3);