It’s rare when conducting interviews in five-star London hotels that a filmmaker will ask with complete sincerity if anyone’s fired a gun at you. I’m sitting face to face with Alex Garland and Ray Mendoza, the co-directors and co-writers of Warfare, a punishing war movie from A24 that strives for realism, not entertainment. Placing viewers amidst bullets, explosions and the total, utter horror of being present during the Iraq War, the action sequences are substantially more distressing than the climax of Civil War, the duo’s…