Is it possible to be gaga for Gaga but not her movie? If we’re talking the third remake of “A Star is Born,” the answer is an unequivocal yes.As an aspiring chanteuse improbably swept off her feet by a shaggy, drunken rock star, Lady Gaga more than holds her own in a role previously reserved for Hollywood luminaries Barbra Streisand, Judy Garland and Janet Gaynor.