CHICAGO — The romantic comedy “Fire Island” is a very gay, very horny, very charming riff on Jane Austen’s “Pride and Prejudice” set on present-day Fire Island in New York. There is banter aplenty, a lot of it dirty. Both sweet and filled with spiky humor, it comes from screenwriter Joel Kim Booster, who also stars alongside Margaret Cho and “Saturday Night Live” cast member Bowen Yang, the latter of whom is one of Booster’s closest friends — on screen and in real life. Though it touches on everything from beauty standards to classism to racism — the snobs in the film are ripped, white and obn…
