dependencies api: Proactively parse lockfiles in background

Created by: efritz

Once #31639 (closed) has been implemented, simply calling the dependencies service method with missing repositories should write through to the database layer as a cache. This will help us build up a global dependency graph (at the repository level) that can be used to reverse query dependents as well.

Implementation of this issue may open up other concerns about data volume and retention, which should be addressed (or at least planned) prior to customer release.