This 1936 Fred Astaire-Ginger Rogers musical is presented tonight, by co-hosts Robert Osborne and Sally Field, as one of “The Essentials,” and it certainly is. But so is the movie that follows it, another Astaire-Rogers musical masterpiece made one year earlier: 1935’s Top Hat. So sit back, and enjoy the glamour, the music, and the unbridled talent. First up: Swing Time, in which Astaire plays a dancer who aims to impress his fiancé (Betty Furness), but ends up being muc