“The King of Staten Island,” director Judd Apatow tells The Post that total immersion was the only way to capture the 26-year-old comic’s life.Here the Syosset, LI-born director, 52, talks about his summer spent in the borough, hanging out with pal Davidson and his Staten Island neighbors.You know, it’s a place that a lot of people haven’t been to, unless you live there. It doesn’t really have an attraction to draw you.