workflows: add workflow group nodes (workflow-part) #2351
Description
There is an icon next to each workflow for displaying status and providing interaction.
There is not presently an icon next to each group (i.e, directory, workflow-part, parent). This would be handy:
- Multi-workflow interventions (namely clean).
- Representing aggregate state (e.g, are there any paused workflows within the group?)
The main difficulty is working out how to collate workflow states. We already do this with task states, e.g, a family containing waiting and running tasks will have a running icon, a family containing running and failed tasks will have a failed icon. However, this is a tad trickier for workflows (what should take precedence?).
It has been suggested we could use combined state icons to convey this, e.g: ⏯
Closely related to #2170