By Sinéad Carew and Niket Nishant (Reuters) -Wall Street indexes closed up on Monday with the Nasdaq leading gains as investors bought heavyweight technology stocks and shrugged off the uncertainty of a potential U.S. government shutdown and hawkish remarks from Federal Reserve officials. Technology provided the benchmark S&P's biggest boost as investors bet on growth from artificial intelligence and expectations that the Fed will keep cutting interest rates as it grapples with persistent inflation conce ...