UI: Workflow of Workflows representation

# Summary

Currently a workflow of workflows (using the resource template) creates a seperate workflow representation in the UI with no form of reference or link between the created workflow and the "parent" workflow. Having some way to see the entire workflow of workflows as a single UI visualization would be great.

Terms:
Parent referrers to any Workflow that creates a workflow
Child referrers to any Workflow created by a (parent) workflow

Ideas for implementation:
- Add a parent setting to the workflow spec, the parent setting can be filled in with a workflow name and a step name for what workflow created it. This is simpler than a children setting given that the parent when creating the child knows it's own name, however a child's name isn't always known by the parent due to generated names.
- When a workflow step has children display them in the UI Workflow view visualisation, timeline, etc.

# Use Cases

This can be used for visualising and calculating complicated Workflow of Workflows scenarios where workflow templates aren't feasible, such as dynamically created workflows.

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**Message from the maintainers**:

Impacted by this bug? Give it a 👍. We prioritise the issues with the most 👍.

Start by tracing the workflow spec and resource-template creation path, then inspect the UI Workflow view visualization and timeline mentioned in the issue. Done means parent and child workflows are linked and the complete workflow-of-workflows relationship is visible in those UI views.

Written by the indexing model from the issue text.