NEW YORK — In the past month, the New York City Police Department has described alarming crimes involving young men living in the city’s migrant shelters. A 15-year-old boy, police said, shot at an officer in Times Square and hit a tourist. Two officers were kicked and punched on West 42nd Street. A Venezuelan man oversaw a ring of criminals who rode mopeds and snatched purses and cellphones from more than 60 people, most of them women walking alone. During an early-morning police raid last week