CHICAGO — A front-runner to fill the Supreme Court seat vacated by the death of Justice Ruth Bader Ginsburg is a federal appellate judge who has established herself as a reliable conservative on hot-button legal issues from abortion to gun control. Amy Coney Barrett, a devout Catholic, is hailed by religious conservatives and others on the right as an ideological heir to conservative icon Antonin Scalia, the late Supreme Court justice for whom she clerked. Liberals say Barrett’s legal views are too heavily influenced by her religious beliefs and fear her ascent to the nation’s highest court could lead to a scaling back of hard-fought abortion rights.