WASHINGTON, March 4 (Reuters) - The newly independent state of Kosovo will need an estimated $2 billion dollars in foreign aid over the next few years, about half of which should be provided by Europe, a senior U.S. official said on Tuesday. The rest of the money could come from the United States and such institutions as the World Bank and International Monetary Fund, Assistant Secretary of State Dan Fried said. He was testifying before the Senate Foreign Relations Committee. Helping the fledgling state, which declared independence from Serbia on Feb. 17 with strong backing from Washington, will require top-level...