The New York Pops hosts “Words and Music: Diane Warren” April 28 at Carnegie Hall. Photo: Amanda Demme for New York Magazine/ One sunny spring afternoon in Hollywood on the third floor of the office building she owns, the songwriter Diane Warren sits at the long console of her dark, windowless recording studio. Behind her chair is a shelf arrayed with several items that reflect her personal ethos — there are two statues of hands flipping the bird, a service call bell labeled “Shut the Fuck Up,”