A behind-the-scenes documentary has revealed some of the big-name celebrities who turned down roles in the epic musical film which tells the story of Jennifer's on-again, off-again romance with her now-husband, Ben Affleck. Taylor, 34, as well as Ariana Grande, Lizzo, Jason Momoa, Jennifer Coolidge and Snoop Dogg were all among the celebrities who either declined to take part or were unavailable. Khloe Kardashian was also invited to make a cameo appearance, but did not. The documentary further explains that High School Musical star Vanessa Hudgens…