Honor .gitignore files

Right now some of the glob expansion that Warp does, doesn't always follow the ignored files, so sometimes we pick up files that don't end up as part of the official sources.

This happened while pairing with @diogomqbm, and we found out that there was a folder in the BEAM tricorder that had just been ignored, but locally it was being picked up by warp and building.

Edge case, but good to consider this more generally.