By Kaori Kaneko TOKYO (Reuters) - Japan and the United States have agreed on a deal to allow Tokyo to join talks on a U.S.-led Asia-Pacific free trade pact that Prime Minister Shinzo Abe is making a keystone of his strategy to open Japan's economy and spur long-sought growth. The agreement brings Japan closer to entering talks on the Trans-Pacific Partnership (TPP), which Japan hopes to participate in as early as July. "Japan and the United States have reached an agreement on Japan's participation in the TPP talks," Abe told reporters on Friday after a meeting with cabinet ministers. ...