In a coup for the Denver Film Society, the director and co-star of the heavily buzzed-about film “La La Land” will attend the opening night of the Denver Film Festival, organizers announced Tuesday. Emma Stone, who co-stars in the Hollywood-set musical extravaganza alongside heartthrob Ryan Gosling, will join Oscar-nominated director Damien Chazelle (“Whiplash”) in person for the 8 p.m.