Brian Steinberg Senior TV EditorSusan Zirinsky, the former CBS News chief and longtime leader of its “48 Hours,” is refashioning herself as a streaming-video maven.Zirinsky will lead the new See It Now Studios, a new production unit that will create news, documentary and unscripted programming for the Paramount Plus streaming-video hub, the CBS broadcast network and other networks owned by parent company ViacomCBS.