Arlene Y. Coleman’s initial involvement with the Cook County Bar Association stretches back to her time as a law student. Now a labor and employment litigator, she became president Friday night of the nation’s oldest black bar association. It currently has 420 members, including lawyers and judges.Coleman received the oath of office from Chief Cook County Circuit Judge Timothy C. Evans at the CCBA’s 101st annual awards banquet and instillation ceremony at the Hyatt Regency Chicago.She was raised in a middle-class family …