Separate iRODS client from workflow containers

[theferrit32]

iRODS container handles authentication and connection to iRODS server, and mounting an iRODS directory as a unix filesystem.

Launching workflow which ingests files from iRODS must include step to start iRODS container and mount it as a filesystem into the workflow container. It should be straightforward to expose the authenticated iRODS mount in the iRODS container on an isolated docker network, and then mount it as a volume in the workflow containers.

Need to explore network filesystem protocols, WebDAV/Davrods would be ideal for this use case but its openid authentication is not yet finished. Temporarily could use ftp or nfs.

[theferrit32]

This is now pretty much solved by enabling Docker-in-Docker functionality in the base image. If this becomes a problem or lacks docker features required by a particular workflow, may explore other possibilities.