Create a datafix multitool deployed on Cloud Run Jobs

We currently have a bunch of random tools (and also been writing ad-hoc scripts) for fixing potential sync issues with the database.
Many of these tools require iterating through the entire database, which isn't great to run locally.
I want to make a single 'multitool' that lets us run some potentially useful jobs in a central location.

Possible commands:
- Reprocess vulns (by ID, or by data source) (i.e. [request_worker_update_record](https://github.com/google/osv.dev/blob/master/tools/datafix/request_worker_update_record.py))
- Reconcile Vulnerability, GCS, Alias/Related/Upstream Group for all vulns (or a particular vuln) (this might be specific to Datastore?)
- Recompute coarse version strings for a given ecosystem

There's a little bit of code clean up I want to do before implementing this