NEW YORK — Nearly 70,000 migrants crammed into hundreds of emergency shelters. People sleeping on floors, or huddled on sidewalks in the December cold. Families packed into giant tents at the edge of the city, miles from schools or services. And New York City is spending hundreds of millions of dollars a month to care for them all. This fall, an official in the administration of Mayor Eric Adams referred to the city’s obligation to house and feed the 500 new migrants still arriving each day as “