Transfer store across buckets or services

[noamross]

Move a bucket from, say MinIO and S3, this would, in theory, require a rewriting of git history to make versions match, as they cannot be transferred. This would invalidate the relic cache, but that's ok.

The big idea is to support a workflow where a project starts locally, but versioned, and is transferred to a shared or public platform.

Other related ideas: get all versions from the bucket, store them in a transferable folder structure.

Now that rclone can serve a folder as S3, can it be used as a store? It doesn't support versions but some directory re-writing could deal with that. Is there a way we could make targets do re-write of cloud folder locations?