The Cinemax cable network's latest edition of Crazy About the Movies, Rita Hayworth: Dancing Into the Dream is, like all the entries in this series, breathless, fan-magazine fluff. This one features narration so hokey it's difficult to listen to (''It's 1927, and movies are the rage for Mister and Missus America....''). Like the Marilyn Monroe documentary Something's Got to Give, which the Fox network offered last month, Dancing Into the Dream is stuffed with frustrating snippets from great old movies you'd prefer to see in their entirety. Fortunately, however, this skimpy portrait of the sultry Hayworth leads off Cinemax's ''Rita Hayworth Week'' a daily double feature Monday through Friday, Jan. 21-25. The Hayworth movies include Gilda, Miss Sadie Thompson, Blood and Sand, and the hot-hot-hot Affair in Trinidad. Skip the salute; enjoy the real thing.