Roger Ailes died in May 2017, but his legacy lives on in Fox News, the cable network bankrolled by Rupert Murdoch that many have accused of being little more than a mouthpiece for conservative agitprop and an apologist for President Trump. Whether or not Fox News was “responsible” for Donald Trump is a peripheral concern of the new documentary “Divide and Conquer: The Story of Roger Ailes,” opening nationwide this week.