The driver who struck a policeman at a Manhattan crime scene told authorities it was intentional, adding, “F–k these cops, it’s a lesson to him,’’ sources said Friday — with the mow-down caught on shocking video. Sahara Dula — a 24-year-old Brooklynite whose lawyer said mentors kids to stay off drugs — was driving her black Lexus the wrong way on the Upper East Side while high on marijuana Wednesday when she barreled into the NYPD officer, officials and sources said. “I told the cop I wanted to go straight, and he wouldn’t move, so I hit him. I did...