By Francesco Guarascio, Khanh Vu and Thinh Nguyen HANOI (Reuters) -Old foes China and Vietnam, at odds over claims in the South China Sea, declared on Tuesday they want to boost ties and build a community with a “shared future”, just three months after Hanoi upgraded its formal relations with the United States. As Chinese President Xi Jinping visited Hanoi on his first trip as China’s leader to Vietnam in six years, the two countries signed 37 cooperation deals in what can be seen as a triumph of Vietnam’s “Bamboo diplomacy” as both China and the United States vie for influence. After China’s …