“Just how many celebrities have the guts to wear Comme des Garçons on the red carpet?” I’m stealing that opening line from the Women’s Wear Daily coverage on the Met Ball because it was the same question I had before getting a peak at the looks Tuesday morning. This year’s Met exhibit from The Costume Institute honors Rei Kawakubo, the founder and designer of Comme des Garçons. This is only the second exhibition that covers only one living designer’s work, the last being Yves Saint Laurent in 1983. The Met Gala is the annual fundraising event for The Costume Institute, and …