Josh Friedman, executive producer of “Terminator: The Sarah Connor Chronicles,” says his hit Fox series all about characters, but at the same time, it’s all about the actors, too. While some may look at the additions of Brian Austin Green from the original “90210″ and rock artist Shirley Manson as stunt casting, Friedman says there’s far more to it, and they had to go through the same auditions as everyone else to land their roles. “I’ve known Shirley well cor a couple years, and known her off and on for many years as she’s a friend of my wife,” Friedman told reporters during a conference call Thursday that included SyFy Portal. “Personally, I’ve always enjoyed her and known her as a performer. And as we were doing the show last year, I used to joke with her about coming on the …