Around 9:15 Saturday night, outside a dark warehouse where designer Alexander Wang presented his 10th anniversary collection, Nicki Minaj emerged inconspicuously from her limousine. She stood alone, unnoticed, and unsure of her next move—where were the cameras?—until a single bulb flashed from behind. “Come around to this side!” she screamed at the lens, pointing out in front of her: she’d give him one shot, and was evidently prepared to make a scene for it to be the best head-to-toe picture t