Trench coats, the perfect pair of jeans, a leather motorcycle jacket, a strand of pearls. In fashion, the most versatile items become the most iconic. The same goes for screenwriting. The magic trick of 2006’s “The Devil Wears Prada” was that it contained razor-sharp insights about the worlds of media and celebrity, packaged as a glossy fish-out-of-water story led by Meryl Streep and Anne Hathaway. Aline Brosh McKenna wrote that “sparkling” script, as Streep called it in her Golden Globes acceptance speech for playing the Anna Wintour surrogate Miranda Priestly, and returned as scribe for this weekend’s box office champ, “ The Devil Wears Prada 2 .” Brosh McKenna brings us a portrait of modern media once again. Only this time, she paints a portrait of an industry mired in debt, battling for relevance and (mostly unsuccessfully) staving off acquisition by soulless tech oligarchs looking for another transaction. It’s a reality that many in Hollywood usually go to the movies to escape.…