NEW YORK — For years, decades even, allegations swirled that R&B superstar R. Kelly was abusing young women and girls, with seeming impunity.They were mostly young Black women. And Black girls.And that, say accusers and others who have called for him to face accountability, is part of what took the wheels of the criminal justice system so long to turn, finally leading to his conviction Monday in his sex trafficking trial. That it did at all, they say, is also due to the efforts of Black women, unwilling to be …