[Fix] no-unused-prop-types: handle optional chaining

[hank121314]

Handle optional chaining in usedPropTypes.

Before:

const Hello = props => {
  const firstname = props?.name;
  return <div />;
};

Hello.propTypes = {
  name: PropTypes.string.isRequired, <<< 'name' PropType is defined but prop is never used eslint(react/no-unused-prop-types)
};

After this pr the error should be resolved.

[ljharb]

Thanks!

[ljharb]

I'll have the fix released later today.

[ljharb]

v7.20.2 is released.