The Trump administration threatened on Tuesday to withhold federal funding from New York’s mass transit network if the Metropolitan Transportation Authority did not respond to a series of demands about efforts to prevent crime on the city’s subway and buses. Sean Duffy, the transportation secretary, said in a letter that the M.T.A. must provide a long list of details about crime in New York City’s transit system, including expenditures on programs to combat it, or face the prospect of losing an untold sum of federal funding.