Cameras are rolling on “ Legacy of Spies ,” the BBC and MGM+’s return to the clandestine world of John le Carre’s beloved Cold War spymaster Michael Smiley, with a bumper crop of names having been added to the cast. Adapted from le Carré’s global bestseller “The Spy Who Came in from the Cold,” and drawing on material his 2017 novel “A Legacy of Spies,” the eight-part thriller is showrun and written by Stephen Cornwell (“Message from the King,” “A Most Wanted Man”) and Clarisa Ingram. Michael