A deranged man sucker-punched an NYPD officer on a Brooklyn sidewalk, pinning the cop to the ground and refusing to budge, body camera footage obtained by The Post shows. The wild video shows Steven Haynes, 40, socking the uniformed officer across the face outside a Bank of America near the corner of Livingston St. and Court St. in Downtown Brooklyn on Thursday, officials said. Haynes, who police said had been sitting on the sidewalk drinking and blocking pedestrians, briefly brawls with the officer before wrestling him to the pavement in a swift attack that sends a nearby trash can flying...