By Joshua Browne Former Arsenal midfielder Granit Xhaka remains optimistic about the club’s chances of winning the Premier League for the first time in 20 years, despite last weekend’s disappointing defeat to Aston Villa. The Gunners were surprisingly beaten 2-0 at the Emirates Stadium on Sunday and crashed out of the Champions League three days later after losing 3-2 on aggregate to Bundesliga giants Bayern Munich. Arsenal’s defeat to Villa was all the more frustrating as Liverpool also slipped up against Crystal Palace, with the dropped points for both handing Manchester City the advantage i…