Nick Vivarelli International Correspondent“Game of Thrones” co-executive producer Vince Gerardis is developing “Provvidenza,” a prequel to Italy’s national literary classic “I Promessi Sposi” (The Betrothed) to be set in a 16th-century plague-stricken Milan that is dirty, dark, lethal and corrupt.After setting up a Rome-based company called CIAO, Gerardis — who specializes in packaging big world-building film and TV projects based on literary properties, such as “Game of Thrones” — has now