lib: Small packagekit.js cleanups
lib: Small packagekit.js cleanups

Import superuser.js with a relative path, so that this works when this
file is copied to subscription-manager.

Drop the unused `runtime` argument from the `Finished()` handler to
pacify eslint in subscription-manager.

mvollmer/cockpit,martinpitt/cockpit,cockpit-project/cockpit,martinpitt/cockpit,garrett/cockpit,martinpitt/cockpit,garrett/cockpit,martinpitt/cockpit,martinpitt/cockpit,mvollmer/cockpit,mvollmer/cockpit,cockpit-project/cockpit,cockpit-project/cockpit,garrett/cockpit,mvollmer/cockpit,cockpit-project/cockpit,garrett/cockpit,garrett/cockpit,cockpit-project/cockpit,mvollmer/cockpit