Iteratively resolving files paths could be slow

[juanca]

Especially going through the possible gem paths.

Ohboy.

[juanca]

After dealing with other tools for migrating a pretty big Rails application to Webpack modules, this is the best strategy (if this is even an issue):

For every known Rails modules path (vendor, gems, etc), get all the trees of files and use it as a lookup. This avoids attempting to read from disk many times. It also stresses the point that is loader should only be used as a transitionary tool.