It has been eight long years since Attack the Block invaded theaters, and its fans have waited for Joe Cornish's next film ever since. I was as surprised as anyone when it was announced that Cornish would direct a children's film about the Knights of the Roundtable as his long-delayed sophomore project, and when the trailers for The Kid Who Would Be King finally arrived last fall, I was more than a little skeptical. However, I felt strongly that Cornish deserved the benefit of the doubt thanks to his first film, and to be completely honest, I …