There’s a quiet, breathtaking power to Alexander Nanau’s documentary “Collective,” Romania’s official Oscar entry this year. A propulsive urgency propels the film along, derived not from manipulative storytelling techniques, but simply facts, information carefully observed, imparted plainly and with such a lack of melodrama, you could miss something crucial if you aren’t paying attention to every word. Because what’s at stake in “Collective” are facts themselves, in the wake of a deadly 2015 nightclub fire in Bucharest, Romania, a crisis that revealed entrenched corruption at every level of th…