WASHINGTON — Ketanji Brown Jackson is heading to Capitol Hill for an audition of sorts. Lawmakers are grilling her about her nomination to become a federal appeals court judge. But if the hearing goes well, the 50-year-old could someday get a callback for an even bigger role: Supreme Court justice.Jackson is one of five judicial nominees appearing before a Senate panel Wednesday, the opening act in President Joe Biden’s effort to put his mark on the bench after four years in which President Donald Trump chose …