Tests: Add missing file provider tests

[pozylon]

GridFS:

• [x] Sign Upload
• [x] Upload with signed Stream (REST Handler, tested)
• [x] Upload from URL (tested with bulk import)
• [ ] Sign Download (private)
• [ ] Download from Stream (REST Handler)
• [ ] Remove Binaries

Minio:

• [ ] Sign Upload
• [ ] Upload with signed Stream (directly to s3-compat bucket) & REST Handler for Webhook
• [ ] Upload from URL
• [ ] Sign Download
• [ ] Download from Stream (directly from s3-compat bucket)
• [ ] Remove Binaries

[pozylon]

Actually this is already done mostly for the gridfs plugin, minio tests can be postponed to v5