When Bette takes time off from mega-hit Hello Dolly! on Broadway, guess who steps in? And who could even hope to come close to filling her shoes? Thank goodness the producers (and Donna Murphy fans) knew who to call. Here's what the incomparable Ms. Murphy brings to the part, says critic David Rooney of The Hollywood Reporter in his smart and enthusiastic rave review: Alternate casting doesn't get more deluxe than Donna Murphy, who's been stepping in during vacation weeks for