TOKYO — Such was the power of the magnitude 9.0 earthquake on March 11 that it bent the tip of Tokyo Tower, the 1,093-foot Eiffel-like structure that has stood as the symbol of Japan’s postwar rebirth for half a century. For the first time since it was erected in 1958, the tower no longer points directly upward, the direction that Japan followed for much of its history after World War II.