By David Ljunggren and Promit Mukherjee OTTAWA, Jan 28 (Reuters) - The threat to the independence of the U.S. Federal Reserve is boosting economic uncertainty ​around the world, Bank of Canada Governor Tiff Macklem said on ‌Wednesday in his strongest comments to date on the outlook for the Fed. U.S. President Donald Trump has ‌repeatedly criticized Fed Chairman Jerome Powell, demanding he cut interest rates. He is seeking to remove Fed governor Lisa Cook while the Department of Justice has threatened Pow ...