[web-scripts] automatically detect config files #39
Description
To make it more straightforward to use web-scripts, treat config the same as kcd-scripts does, which means that if a config override file exists in the package, you should use it instead of the base config.
This will require checks like this for every script: https://github.com/kentcdodds/kcd-scripts/blob/master/src/scripts/lint.js#L11-L15