By Nicolás Misculin and Candelaria Grimberg BUENOS AIRES (Reuters) -Argentina libertarian economist Javier Milei was sworn in as president on Sunday in a sharp swerve for the South American country as it seeks a radical fix for the worst economic crisis in decades and inflation rapidly heading towards 200%. Milei, 53, a former TV pundit who shot to fame with expletive-ridden tirades against rivals, China, and the pope, took the presidential sash from outgoing Peronist Alberto Fernandez in a packed Congress with crowds gathered outside. The wild-haired outsider marks a major gamble for Argentin…