WASHINGTON (Reuters) -The city of Washington, D.C., sued right-wing groups the Proud Boys and Oath Keepers on Tuesday, seeking to collect on the financial costs of the deadly Jan. 6 attack on the U.S. Capitol and its aftermath. The suit aims to hold accountable the groups that helped to organize a rally by thousands of supporters of then-President Donald Trump that evolved into an assault on Congress aiming to stop it from certifying Democrat Joe Biden's election victory. District of Columbia Attorney General Karl Racine told reporters the defendants had caused physical and financial harm to Washington and its residents,...