Bridget Jones, beloved Singleton and global phenomenon, is back with a bump in Bridget Jones's Baby: The Diaries.      8:45 P.M. Realize there have been so many times in my life when have fantasized about going to a scan with Mark or Daniel: just not both at the same time.     Before motherhood, before marriage, Bridget, with biological clock ticking very, very loudly, finds herself unexpectedly pregnant at the eleventh hour: a joyful pregnancy which is dominated, however, by