A $1 billion dispute over dozens of masterpieces involving a Russian oligarch, a Swiss art dealer and one of the world’s most powerful auction houses takes center stage in “The Oligarch and the Art Dealer,” Andreas Dalsgaard and Christoph Jörg’s three-part documentary series premiering in full this week at CPH:DOX . The pilot episode debuted earlier this year at Sundance Film Festival. Copenhagen marks the world premiere of the complete series, which traces the decade-long legal battle between