His lyrics have poignantly expressed everything from the inner turmoil of assassin John Wilkes Booth to the life lessons Jack learned when climbing the beanstalk. And the Gay Men’s Chorus of Washingtonis kicking off its 25th Annversary season by giving DC audiences the chance to appreciate his incomparable career. The man in question, of course, is the almost universally-admired Stephen Sondheim, and the chorus’ latest production, “Everything’s Coming Up Sondheim,” takes a one-song sample…