(Reuters) - Online used car seller Vroom Inc filed for a U.S. initial public offering on Monday, at a time when the coronavirus-led restrictions are shifting consumer spending to online platforms. The company said it saw a huge surge in its e-commerce business, with the unit's revenue rising 160% in the first quarter of 2020.Auto retailers have been slow to embrace e-commerce, but the COVID-19 pandemic is forcing dealers to turn to digital tools to close deals without a handshake and arrange for..