By Moira Warburton, Lawrence Hurley and Andrew Chung WASHINGTON (Reuters) -Ketanji Brown Jackson, President Joe Biden’s U.S. Supreme Court nominee, on Tuesday defended her past legal representation of Guantanamo Bay detainees, rejected Republican accusations that she had been lenient as a judge in child pornography cases and vowed to “stay in my lane” if confirmed to the job. During the second day of her Senate Judiciary Committee confirmation hearing, Jackson pledged to be an independent jurist who would not inject her own views into rulings. In responding to Republican claims that she has be…