Rule prop-types should include nextProps checking in shouldComponentUpdate

[amerryma]

Consider this example:

class Hello extends Component {
  static propTypes = {
    bar: PropTypes.func
  }
  shouldComponentUpdate(nextProps) {
    return nextProps.foo !== null
  }
  render() {
    return <div bar={this.props.bar} />;
  }
}

This is a case where we want to check to make sure that foo is properly defined in propTypes. I think this case should be included in the prop-type rule. Any thoughts?

Please refer to my comment here: #1636 (comment)

I've made the changes in a forked repo and seems to work just fine. If we wanted to get this in, I'd need some help with the test cases but here is my fork: https://github.com/mindspacepdx/eslint-plugin-react/tree/am-should-component-update

[ljharb]

A PR would be great :-)