Add GridPane x-grid-srcache-fetch cache header to Site Health checks

x-grid-srcache-fetch

//////////////////////////////////////////////////////////////////////////////
// Add GridPane x-grid-srcache-fetch cache header to Site Health checks
// https://make.wordpress.org/core/2022/10/06/new-cache-site-health-checks-in-wordpress-6-1/
//////////////////////////////////////////////////////////////////////////////
add_filter( 'site_status_page_cache_supported_cache_headers', function( $cache_headers  ) {
    // Add new header to the existing list.
    $cache_headers['x-grid-srcache-fetch'] = static function ( $header_value ) {
        return false !== strpos( strtolower( $header_value ), 'hit' );
    };
    return $cache_headers;
});