Implement API to move data from block storage to Egress bucket

[LakshithadeSilva]

Implement a REST API to move objects in /data to the 'egress' bucket.

[JimMadge]

Same thought about using a workflow template as #128.
What we might need from the API is a function to retrieve outputs from the egress bucket.

[craddm]

See #128, similar thoughts here. Note that you can have output artifacts with argo workflows too, so it can be configured to automatically copy outputs to an s3 bucket.

The API does already have a function to retrieve outputs from the argo-artifacts bucket, which is the only one that currently exists, so it'll be easy to adapt