Offer a "minimal" version with less dependencies

[d-fischer]

There should be a more minimal (or "base") package offered that gets rid of a few dependencies:

• parse-json could be replaced by JSON.parse - the former improves error messages, but if you don't want that, the latter reduces the dependency impact to zero since it's included in the standard library
• import-fresh could be replaced by just calling require - similar to above, the advantage of the former being that file changes during the runtime can be respected
• js-yaml could be removed, making YAML support optional

This would leave us with only two dependencies, env-paths and path-type, which each have no dependencies of their own. (We can probably also get rid of path-type, but that's a separate concern.)

The end goal would probably be that there is a "base" package, and the "full" package depends on that, adding and replacing default loaders to achieve the current state of cosmiconfig (i.e., this should not contain any breaking changes).

Offering this, we will either have two repositories or a monorepo.

You should be able to use the "base" package and still add back a YAML parser, parse-json or import-fresh as you like.

It is important to note that it should be possible to ignore searchPlaces that do not have loaders attached to them due to the mentioned removal of YAML support in the "base" package. If you add a YAML parser (or the "full" package does), the searchPlaces should be in the exact state that is currently in the code.