Fashion’s pull east shows no signs of slowing. Brands from Chanel to Gucci and Isabel Marant have been setting up shop in the Hamptons this summer and last Friday evening, Zegna and Mr Porter were the latest to get in on the action. Zegna is the headliner of the latest installment of Mr Porter’s summer campaign, titled “Al Fresco,” a partnership that was celebrated Friday evening with a party at the…