NEW YORK — General Motors agreed to pay $900 million and submit to a monitor in a deal with the government in which it admits that a deadly problem with small-car ignition switches was hidden from the public for over a decade, authorities announced today.The agreement calls for two criminal charges to be dismissed after three years if the automaker cooperates fully.Also today, GM announced that it will spend $575 million to settle many of the civil lawsuits filed against the company over the ignition switch problems. …