Upon taking over from the outgoing director, John Cooper, last February — a promotion that made her both the first woman and the first person of color to head Sundance — Jackson said she wondered what she could bring to the world’s most venerated independent-film festival. Movie theaters across the country were soon shuttered, and some of the most talked-about titles to come out of Sundance 2020, like the raucous comedy “Zola,” were pulled from the calendar and still have no release date. By June, Jackson knew she would have to plan for a Sundance that would play out primarily on the internet. 