“Lovers Rock” may be the bolder movie, but, in “Mangrove,” director Steve McQueen runs circles around Aaron Sorkin’s “other” 2020 courtroom drama - this, my friends, is how it’s done. The film, based on the true story of the "Mangrove 9," focuses on a group of nine black protestors who clashed with police during a march in London in 1970, they were subsequently arrested and put on trial. “Mangrove,” depicting that trial, is proof that you can make high art out of such a tiresome genre. Vital, powerful and resonant, McQueen is such a master. It’s part of the director’s upcoming “Small Axe” miniseries (10.20.20), and is the second episode to screen at the New York Film Festival, after “Lovers Rock. Next week, “Red, White and Blue,” starring John Boyega, will premiere.