“Fresh Off the Boat” actress Constance Wu has come out about being raped in her 20s, relating the incident in a powerful essay Monday. It happened on a second date with “Ty,” an aspiring novelist who invited her up to his apartment for a “gift” that proved to be “an original 20-page medieval fantasy in which I was the central character,” wrote Wu, 40, in her new book, “Making a Scene.” “A fantasy he’d written after one date.” She had agreed to go upstairs to his apartment to receive this gift, ignoring a “twinge of warning in my gut.” It was there that he plied her with the gift-wrapped box, d…