If Arsenal had a striker like Newcastle United’s Alexander Isak, they might be Premier League champions right now. But the Gunners have ended the season as runners-up, with Manchester City clinching the title on the final day. They now have the chance to do the double, as they face Manchester United in an FA Cup final that is very important for Newcastle United and their European aspirations. As for Arsenal, they are trying to work out how they can go again next season and challenge Man City for the ultimate prize in English football. Mikel Arteta knows that means getting a consistent goalscor…