feat: fetch base config using configdir

[josegonzalez]

At the moment, config defaults are specified here, but we should attempt to read defaults from standard paths via configdir.

One thing is that the default LocalPath on linux should probably be /etc/default, though keeping the library as is may be okay...

I'm not sure if we should use json as the file format for the options or something else. If there is a library for reading default files, that might be cool to use, but not super necessary. Json files would make it easy to update.