Patricia Arquette Is an actress of such promise ("True Romance," cable TV's "Wildflower") that you anticipate a career peak from her teaming with director John Boorman ("Deliverance," "Hope and Glory"). Think again. Arquette is disappointingly one-dimensional as Laura Bowman, an American doctor who finds her husband and son murdered and flees her home and job to forget. In 1988, Laura travels with her sister (Frances McDormand) to Burma, where she is untouched by the country's lush beauty or its