Keep pkg/lib in the same location as it is in the cockpit repository,
and adjust the include path accordingly.
This makes the production of the .pot file somewhat more deterministic:
previously, it would either include or not include the strings from
pkg/lib depending on if it had been checked out or not. Now it never
includes them.
Cherry-picked from cockpit-podman commit a70630be2139a.
This code comes from cockpit.git. Newer ESLint versions have a lot of
complaints about it, but in starter-kit we can't do anything about these
directly. Let's keep the stricter ESLint settings instead of ignoring a
lot more warnings to cover src/lib.