PARK CITY, Utah (AP) — Charli xcx plays herself in “The Moment,” a meta mockumentary about the end of Brat summer and grappling with otherworldly success. “I was just really interested in telling this story about expectation,” Charli xcx told The Associated Press the day after “The Moment” debuted at the Sundance Film Festival. The 33-year-old pop star from Essex has been in the music industry since she was 16, with a career trajectory that she described as anything but straight forward. Then,