WASHINGTON — Not long after Senator John McCain learned last summer that he had terminal brain cancer, he began convening meetings every Friday in his Capitol Hill office with a group of trusted aides. The subject was his funeral. He obsessed over the music, selecting the Irish ballad “Danny Boy” and several patriotic hymns. He choreographed the movement of his coffin from Arizona, his home state, to Washington. And in April, when he knew the end was coming, he began reaching out to Republicans, Democrats and even a Russian dissident with requests that they deliver eulogies and serve as pallbearers....