Arvados

The workflow mounts now generally consists of a wrapper workflow that runs a workflow stored in a collection. WB2 should extract that collection PDH and provide a link to it. (The registered workflow panel already does this, there's probably a method that can be reused).

WB2 should also link to the registered workflow that was used -- although the registered workflow can be modified after it was used, in which case we want to indicate that the upstream version has been updated.