“Dancing the Twist in Bamako,” a new feature film from French director Robert Jules Guédiguian, is a conundrum. If ever there was a movie intended to push some hot buttons, surely this is it. What contentious subject doesn’t the picture glance upon? You name it, Mr. Guédiguian brings it on: colonialism, racism, socialism, capitalism, Islamism, sexism, and, undoubtedly, at least one -ism I’ve left off the list.