U.S. District Judge Sharon Johnson Coleman’s busy federal courtroom leaves her responsible for resolving difficult legal and factual issues.But sometimes the perks of being a judge exist where there’s no decision left to make.“It does have a uniform,” Coleman quipped. “I don’t have to worry about how I dress.”Now 22 years into her judicial career — first in Cook County court, then on a state appellate court and ultimately the federal district court — Coleman said being …