File manager for Cloudflare R2

[crqch]

Currently any files stored in R2 need to be manually uploaded by me, via the Cloudflare Objects web editor. With efforts to change this website and make it more dynamic, we first shall focus on files management service, so members of KSI can upload them.

This feature would require the following:

• Creating database models to represent objects in R2 storage (for caching purposes, to limit Class B operations on R2)
• Adding new endpoints and helper classes to the backend, with partial CRuD over the files, adding batch operations such as deletion and upload, keeping tombstone objects for history/backup purposes (we do have 10GB of free storage anyway), limiting certain directories to subgroups, council etc. All images should be automatically optimized losslessly. Only certain file types should be allowed.
• Adding a frontend integration to backend endpoints - a paginated table with objects' info, including who uploaded the object, a small thumbnail for preview (it could scale up on hover)
• Updating S3Cache class to properly index objects from the added database models