It was a marriage made in box-office heaven. Woody Allen, the prototype of the self-effacing schlemiel, and Bette Midler, the quintessential loud-mouthed broad, play a couple celebrating their 16th wedding anniversary in "Scenes From A Mall," which just wrapped up shooting in Stamford, Conn. This time, however, the two stars stray from their traditional shtik, says Paul Mazursky, who wrote and directed the film. Midler plays a psychologist who just wrote a best-selling book; Allen is a lawyer. The title is a play on Ingmar Bergman's "Scenes from a Marriage"--which ought to tickle Bergman fan Allen.