Robert K. Hur will walk into a Capitol Hill hearing room on Tuesday as a uniquely unifying figure in divided Washington — a man disdained by Democrats and Republicans alike.In February, Mr. Hur, the special counsel who investigated President Biden, concluded a yearlong investigation into Mr. Biden’s retention of sensitive government documents by finding that the president should face no criminal charges.But Mr. Hur, using language Mr. Biden’s team saw as gratuitous, politically damaging and outside his job description, described the octogenarian president as “a sympathetic,…