Arvados

Goal: have arvados-cwl-runner execute CWL files from a git branch as written, avoiding the "packing" step.

Execution:

1. crunch-run can mount git repositories (#8311)
2. arvados-cwl-runner, running inside container, uploads file references to Keep and updates internal workflow references to maintain job reuse.

UI:

1. User loads the CWL file in Composer
2. Pushes a "Run" button
3. Composer creates a container request
   1. Puts minimal input description in "workflow.json" where workbench knows to look for it
   2. Put real workflow at a different mount point with reference to git repo & commit
   3. Command line references real workflow
4. Composer opens workbench page for container request in a new tab