Add ability to close modal with ESC key

[mbrookson]

This would be a useful addition to help move around the UI with just the keyboard.

[manfromanotherland]

Maybe something like this would work?

const keyboardShortcuts = useCallback((event) => {
  if (event.keyCode === 27) {
    closeModal();
  }
}, []);

useEffect(() => {
  document.addEventListener('keydown', keyboardShortcuts);
  return () => document.removeEventListener('keydown', keyboardShortcuts);
});

[mbrookson]

@EdmundoJr Thanks for the suggestion! I've not tried it but it looks reasonable. Feel free to PR a change, otherwise I will try to get round to implementing this in the near future.