Among the matches played by Royal Challengers Bangalore, what is the match ID of the match with the highest winning margin?
Royal Challengers Bangalore refers to team_name = 'Royal Challengers Bangalore'; highest winning margin refers to MAX(win_margin)
SELECT T2.match_id FROM Team AS T1 INNER JOIN Match AS T2 ON T1.team_id = T2.match_winner WHERE T1.team_name = 'Royal Challengers Bangalore' AND T2.match_date LIKE '2012%' ORDER BY T2.win_margin DESC LIMIT 1