Cross-dressing teens from Harvey Milk High School offered sex for money in Greenwich Village and then robbed the would-be johns ? by pretending to be cops, sources said last night. The boys, all passing themselves off as ladies of the evening, took money and credit cards from at least six men, sources said. Five youths were arrested yesterday in the scam, which cops say went like this: The students from the Astor Place high school for gays and lesbians promised men cruising the Village various sex acts for money. Once the men stopped, the students flashed fake NYPD badges and...