While Kanye West was playing court jester in the Oval Office last Thursday, bragging about having an IQ in the 98th percentile and revealing that wearing a Make America Great Again cap made him “feel like Superman,” Sylvie Simmons, author of “I’m Your Man: The Life of Leonard Cohen,” was discussing her favorite subject’s recent act: trolling the Trump-loving rapper from beyond the grave. Cohen, the deep-voiced troubadour who wrote some of rock’s most widely admired lyrics —“Suzanne,” “Bird on a Wire” and “Hallelujah”— died November 7, 2016, at age 82. But his new book, “The Flame: Poems Notebooks Lyrics Drawings,” debuted last week, powered by a poem that roasts the rapper—”Kanye West Is Not