WASHINGTON — Legal experts and interest groups are weighing in on Ketanji Brown Jackson as the Senate Judiciary Committee began a fourth day of hearings on her historic nomination to become the first Black woman on the Supreme Court.Jackson faced down a barrage of Republican questioning over two days about her sentencing of criminal defendants, her bid to join the Supreme Court veering from lofty constitutional questions to attacks on her motivations on the bench.On Thursday, the last day of hearings, interest groups …