Holding that (1) because the Petitioner was removable based on his commission of an aggravated felony or specific firearm offense, whether Petitioner established, for CAT relief, that the government would acquiesce in his torture is a mixed question of law and fact that falls outside of the Fourth Circuit's jurisdiction pursuant to 8 U.S.C. § 1252(a)(2)(C) and (2) the immigration judge’s determination that Petitioner failed to establish government acquiescence is subject to de novo review, rather than clear error review, by the BIA.