Entertainment | Legacy | News Roundups    “Ed Koch!” The voice on the phone was not so much identifying itself as trumpeting an introduction. This was Ed Koch, all right, barging into our phone conversation with the same ebullience that characterized his three terms as New York’s most popular and controversial mayor since Jimmy Walker. I caught up with Koch on January 10, at his modest Greenwich Village apartment. I can’t definitively say mine was the absolute last interview Koch granted before his death early …