NEW YORK — Government Sachs is returning to Washington. After a decade in the wilderness, Wall Street’s most powerful firm, Goldman Sachs, is dominating the early days of the incoming Trump administration. The newly picked Treasury Secretary, Steven Mnuchin, spent 17 years at Goldman. Trump’s top incoming White House adviser, Steve Bannon, spent his early career at the bank. So did Anthony Scaramucci, one of Trump’s top transition advisers. Goldman’s president, Gary Cohn, spent an hour schmoozing with President-elect Donald Trump on Tuesday and could be up for an administration job, possibly as director of the Office of Management and...