By David Jeans NEW YORK, March 18 (Reuters) - Erik Prince, the founder of private military firm Blackwater, is backing a Ukrainian drone technology firm he wants to help ‌sell to the U.S. military, underscoring Kyiv’s rising role as a hub of innovation ‌in modern warfare. Prince, who last year joined the board of Ukrainian drone software firm Swarmer, told Reuters that four years ​of war with Russia had allowed Ukrainian defense companies to rapidly develop low‑cost drones, software and electronic warfar ...