KKR & Co. founder Henry Kravis, Blackstone Group LP Chairman Stephen Schwarzman and Carlyle Group co-founder David Rubenstein were among the guests when Kazakhstan President Nursultan Nazarbayev hosted a dinner in New York. Apart from the dining at the Four Seasons Hotel, there was access to a possible $93 billion on the table as Nazarbayev, who presides over Central Asia’s biggest energy exporter, seeks to boost returns on the country’s wealth...