Reinstate image thumbnail column

[AetherUnbound]

Description

The image thumbnail column was removed from the ImageStore interface (and several providers) as part of WordPress/openverse-catalog#526. Since that time, we have come to a better understanding of the data stack as a whole and would like to continue using upstream-provided thumbnails where possible to reduce load on our own thumbnail service. This Make WP post provides some additional context: https://make.wordpress.org/openverse/2022/10/25/storing-provider-supplied-thumbnails/

After discussing this on the post, we have come to the decision to reinstate the thumbnail field on ImageStore and start using the thumbnail column in Postgres once more. We should also go back and re-add the thumbnail ingestion to the provider scripts that were modified in WordPress/openverse-catalog#526.

Once this is complete, this will also unblock #1401, #1389, and #1450.

Additional context

Implementation

• 🙋 I would be interested in implementing this feature.

[AetherUnbound]

I've set this issue as "high" because it's blocking a few other issues. If medium makes more sense for this please go ahead and change it!