By Katie Catherall Manchester United legend Wayne Rooney believes youngster Kobbie Mainoo will be key for England’s chances of success on Sunday when they take on Spain in the Euro 2024 final. The Three Lions will play in their second successive Euro final when they travel to Berlin to face Luis de la Fuente’s side, with hopes of finally ending their wait for European silverware. Their performances so far in the tournament have received mixed reviews, but Red Devils star Mainoo has been the subject of praise from both fans and pundits. The 19-year-old has featured in five of his nation’s six g…