Could there be a better week for Sacha Baron Cohen to release a film called “The Dictator”? A few days ago, Cohen parked a camel in Cannes, in what seemed like the first act of a cult of personality. Pairing a touch of showmanship, a frisky film, and the spotlight of the festival, the star of “Borat” all but declared himself the worldwide ruler of comedy. Like many public rituals under totalitarians, “The Dictator” is long on stagecraft but a little