More than six years after the right-wing extremist set off a car bomb in Oslo that killed eight people and shot 69 more to death at a summer youth camp, “[Erik] Poppe, one of Norway’s best-known directors, has channeled his outrage into a film, U – July 22, the first cinematic depiction of the attack. The movie, which opened in Norway on Friday, has prompted a wider debate about the ethics of fictionalizing the traumatic event.”