--fix with file-extension-in-import can break imports of packages

`file-extension-in-import` when configured to require an extension reports the following import as invalid:
```js
import "firebase/app";
```
Using `--fix` changes the import to
```js
import "firebase/app.js";
```
Which is not a file that exists, causing a runtime `ERR_MODULE_NOT_FOUND` error as well as a TypeScript `TS2307` compiler error.