LONDON — Hollywood star Johnny Depp accused his ex-wife, actress Amber Heard, of conducting extra-marital affairs and lying about him beating her up when he appeared in a London court on Tuesday to pursue legal action against a British tabloid newspaper.Depp, the 57-year-old star of the “Pirates of the Caribbean” films, is suing The Sun’s publisher, News Group Newspapers, and its executive editor, Dan Wootton, for libel over an article Wootton wrote in April 2018 calling him a “wife