As the Russia-Ukraine war drags into its fifth year, it’s clear that traditional diplomacy has failed. But an unlikely go-between has stepped into the breach: high-living oligarch Roman Abramovich By Andrew Ryvkin “Three weeks ago, a representative of our business community called me with a question,” Vladimir Putin said at the St. Petersburg International Economic Forum, Russia’s version of Davos, earlier this month. “I’ve known him for a very …