David DiChiera belongs on the Mount Rushmore of contemporary Detroit. With his beloved city at its nadir in the 1970s and ’80s, he dared to imagine a future that was audaciously optimistic and inextricably linked to the arts and downtown Detroit. He promised to build an opera house and a major opera company from scratch in a city better known for producing Chevys than “Carmens.” Most people thought he was nuts. But then he accomplished everything he said he would do.