By Francesco Guarascio and Khanh Vu HANOI (Reuters) -China and Vietnam are set to agree this week on upgraded rail links and other infrastructure, possibly including digital projects, officials said, in moves that would bring Hanoi closer to Beijing as great powers jostle for influence in Vietnam. The announcements are expected during President Xi Jinping’s visit to Hanoi from Tuesday, the first in six years to the Southeast Asian neighbour, and shortly after U.S. President Joe Biden travelled to the Vietnamese capital in September to strengthen bilateral ties. China is ready to offer grants t…