It’s an American fable, durable as “Cinderella” and romantic as “Romeo and Juliet.”In this evergreen Pygmalion story of “A Star is Born,” a famous man discovers and marries a talented young woman, then self-destructs when her star eclipses his.Fredric March and Janet Gaynor were the doomed couple in 1937; James Mason and Judy Garland in 1954 and Kris Kristofferson and Barbra Streisand in 1976.Now Lady Gaga and Bradley Cooper headline this Kleenex-depleting chestnut as Ally Campana …