v3: datadump violet integration

closes #137 (closed)

closes #138 (closed)

closes #128 (closed)

this makes datadump be a full user of violet job queues! 🎉

(it was such a good idea to make the library. i can already feel how good the implementation of other things will be)

TODO

• add GET /api/dump to list old, current, and future dumps for the user
• add the violet_jobs table to our schema file and migration
• add testing of datadumps
• add migrations to delete old datadump-specific tables