What is the collective noun for superheroes? An immodesty of superheroes, perhaps? A bluster, a cluster bomb, a swank? Somebody ought to settle the issue soon, if we’re going to be showered with films like “Avengers: Infinity War.” It has two directors, Joe and Anthony Russo, and characters from every corner of the Marvel firmament. From the top: Iron Man (Robert Downey, Jr.), Spider-Man (Tom Holland), Black Panther (Chadwick Boseman), Black Widow (Scarlett Johansson), Captain America (Chris Evans), Doctor Strange (Benedict Cumberbatch), Falcon (Anthony Mackie), Hulk (Mark Ruffalo), Thor (Chris Hemsworth), Gamora (Zoe Saldana), Nebula (Karen Gillan), Peter Quill (Chris Pratt), Drax (Dave Bautista), Loki (Tom Hiddleston), Wanda the Scarlet Witch (Elizabeth Olsen), and her even redder boyfriend, Vision (Paul Bettany). Apologies if I’ve left anyone out. Among those not…