CNN  —  It’s not a bird or a plane — it’s the latest “Superman” movie soaring towards the top of the box office. Warner Bros. Pictures’ “Superman” grossed an estimated $56.5 million domestically on Friday, on top of $22.5 million in Thursday previews. The 1938 comic book character, which began as a film series in 1978, is expected to gross nearly $130 million domestically for the weekend. Warner Bros. Discovery is the parent company of CNN. “Superman has been one of the most challenging movies