WASHINGTON — President Biden signed legislation Friday forcing railway unions to accept a labor agreement despite worker objections to a lack of paid sick days — hours before hobnobbing with visiting British royals. Biden regularly calls himself the “most pro-union president” in history but asked Congress to intervene Monday, saying the US economy could not bear a railway shutdown. The president will meet Friday afternoon in Boston with Prince William, the heir to the UK crown, and his wife Kate Middleton — creating awkward optics after the president also hosted billionaires and Hollywood stars Thursday night for a lux state...