GitLab

* feat: move options to main package and make internals private

Rationale:

1. This allows us to make private options for testing.
2. This removes an import for DHT users.
3. This makes options much easier to discover.
4. This makes it possible to make the config/options internals private.

We originally put them in a sub-package to avoid poluting the root namespace,
but that isn't really necessary.

This keeps the old package (for now) to avoid breaking too much.