Can migrate LFS objects to S3 style object storage

What

• Allows LfsObjects to be individually migrated to object storage
• Reuses code from https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/1762/diffs?diff_id=4841606#0ef14ca7e447f477230136ca76fb4ab0bed43af4
• Currently provides a rake task for this in the same way as for artifacts, as well as scheduling a ObjectStorageUploadWorker automatically

Why

Reduce space usage and load on git storage disks

Todo

Screenshots (if relevant)

Acceptance criteria

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Conform by the merge request performance guides

Related

Fixes https://gitlab.com/gitlab-org/gitlab-ee/issues/2841