feat: update apiv2 db ingestion to support new s3 schema

[jgadling]

This PR is currently in a DRAFT state because I haven't updated the tests to reflect the latest changes, however the importer should be complete and working.

Some changes to note:

• Annotation importers were refactored to use the new importer base classes because that made it easier to update them to support ingesting a single annotation across multiple voxel spacings
• The Tomogram importer was refactored as well, just to help this migration along.

I've update the test data to look more like real-world data, with zarr files and other extras, basically because it made running the s3 conversion script on our existing test data easier. These files are a little bit out of date as well since they still reflect old file path formats, but I'll update them soon.