React-PropTypes-to-prop-types codemod breaks migrated named import

Using `React-PropTypes-to-prop-types` codemod —

These named exports:
```js
import { PropTypes } from 'prop-types';
```
```js
import { PropTypes as PT } from 'prop-types';
```

...get transformed into this:
```js
import 'prop-types';
```


Codemod basically assumes already migrated stuff to use default export:
```js
import PropTypes from 'prop-types';
```
