Prime Minister Mark Carney of Canada announced on Thursday a sweeping plan to offer billions of dollars in incentives and tax breaks for auto industry investment designed to help turn Canada into a global leader in electric vehicles.The new policies, Mr. Carney said, were meant to transform Canada’s economy and make it less reliant on a single trade partner after President Trump’s economic assaults and threats on Canada’s sovereignty have frayed relations between the two nations.“We must take care of ourselves,’’ Mr. Carney told reporters at an auto parts factory in Ontario. “We cannot control what others do.’’Mr. Trump has...