The federal government plans to sell leases for wind farms off the coasts of Massachusetts, Rhode Island and Virginia, the first time it has sold competitive leases for wind energy on the outer continental shelf, officials said Friday. The leases for the two areas, which total more than 430 square miles, will be sold next year, the Interior Department and its Bureau of Ocean Energy Management said. One area for lease is about 10 miles off Rhode Island’s shore, and the other is about 27 miles off the southern part of Virginia. Officials said each area could be developed to generate enough electricity to power 700,000 homes.