IT'S official. Celtic fans have been declared the best in the world by football's governing body. Fifa yesterday announced that ,000 Celtic supporters who travelled to Seville for last season's Uefa Cup final had been awarded world football's Fair Play award for their ''exemplary, fair, and cordial conduct''. The award follows the equivalent accolade given last August by Uefa for the part the fans played in the team's run to the final, where they were defeated by Porto. The latest award will come as some consolation to fans of the Glasgow club, who were still licking their wounds yesterday aft