Feature: stateful mode for useResize/useIntersection

[krutoo]

Future API idea:

function MyWidget ({ onSeen }) {
  const ref = useRef(null);
  
  // instead callback we pass object with stateless: false to make it stateful
  // (stateless: true by default for backward compatibility)
  const seen = useIntersection(ref, {
    stateless: false,
  });

  return <div ref={ref}>Widget</div>;
}