In less than a week, New York Fashion Week will officially roll into town, turning a wide swath of the city into a carnival of journalists, buyers, bloggers, label-obsessed shoppers and ? most notably ? anxious designers. Isaac Mizrahi will not be among them. At 51, Mr. Mizrahi has moved on, after licensing his name and selling his company to Xcel Brands, evolving from fashion designer to ?polymath ? businessman, entertainer.?