It’s not a reboot, a redo or a sequel. James Gunn’s “The Suicide Squad” is, as Harley Quinn star Margot Robbit put it: “A different thing.” David Ayer’s 2016 “Suicide Squad” might have been a critical disaster, it was still a financial hit. In other words, a second movie was not out of the question. Yes, it features some of the same actors playing the same characters, like Robbie’s Harley Quinn and Joel Kinnaman’s Rick Flag, but it also introduces a host of D-list DC comics villains from Bloodsport, played by Idris Elba, to Peacemaker, played by John Cena.