SPRINGFIELD — A group of Commonwealth Edison ratepayers asked a federal judge Monday to force the utility company, House Speaker Michael J. Madigan and others to pay “at least” $450 million to be split among all those affected by an alleged extortion scandal.The number of affected ratepayers could rise to more than 3.8 million, according to a lawsuit filed by attorneys representing six residents that all resided in the Chicagoland area at some point in the last decade.In an agreement with the federal government to avoid …