Former Arsenal winger, Theo Walcott, has hailed David Raya as the team’s “hero” following their penalty shoot-out win over FC Porto in the Champions League last 16. The Gunners were trailing 1-0 from the first leg. Leandro Trossard scored the only goal of the game at the Emirates, as it eventually went to penalties. Raya, who joined Arsenal on loan from Brentford, saved two spot-kicks to send his side into the quarter-finals. Walcott, speaking on the pitchside, said: “You have to give so much credit to Porto, they have frustrated Arsenal tonight but those key moments, David Raya tonight, he is…