In a region infatuated with competition, politics and personalities, the battle for casino development rights in Greater Boston has all the elements of can’t-miss public theater. Hundreds of millions of dollars are at stake in the all-or-nothing contest among Suffolk Downs, led by lead investor Richard Fields; Wynn Resorts, the firm founded by Las Vegas casino magnate Steve Wynn; and Crossroads Massachusetts, the development company of David Nunes, who crossed last Tuesday’s casino application deadline with 10 minutes to spare.