Create new offline transfer API endpoint to begin offline import

Everyone can contribute. Help move this issue forward while earning points, leveling up and collecting rewards.

• Close this issue

Create a new endpoint to begin the import side of an offline transfer. The API endpoint should be similar to POST /bulk_imports, but it accepts object storage credentials instead of a source destination URL and PAT.

This API begins the offline transfer import similarly to direct transfer, but it calls a new offline service to create a BulkImport using the offline transfer metadata file that should be present on object storage.

This endpoint must be behind a new feature flag for offline transfer imports.