Make babel-loader caching optional

Created by: frontsideair

This line here enables caching, which is nice. But I have a use case where the node_modules is read-only and since .cache folder can't be created, dev server won't start. Here's the output:

Error in ./src/index.js
Module build failed: Error: EROFS: read-only file system, mkdir
'/path/to/project/node_modules/.cache'
    at Error (native)
 @ multi main

If I can override this setting, or at least if Webpack can gracefully recover from this error, it would be great.