NEW YORK — A former high-ranking FBI counterintelligence official who investigated Russian oligarchs has been indicted on charges he secretly worked for one, in violation of U.S. sanctions. The official was also charged, in a separate indictment, with taking cash from a former foreign security officer.Charles McGonigal, the special agent in charge of the FBI’s counterintelligence division in New York from 2016 to 2018, is accused in an indictment unsealed Monday of working with a former Soviet diplomat-turned …