addded family grouping with subgraphs

[markgrahamdawson]

Partly addresses issue https://github.com/cylc/cylc-ui/issues/1130 The grouping of nodes by cycle point is completed in this pr https://github.com/cylc/cylc-ui/pull/1763

----Notes on work----

Some ideas for a unified approach to grouping/collapsing cycles/families. I'm suggesting unifying the handling of cycles and families (note, cycles represent the "root" family so they are essentially the same thing).

Grouping/Ungrouping - Drawing dashed boxes around a cycle/family.

Collapsing/Expanding - Reducing a family down to a single node.

Limitations of the Cylc 7 approach:

• Once you expand a family it's gone, the tasks which belong to the expanded family are mixed in with other tasks in the graph, you can not tell what family they belong to. This is an issue if the user wants to examine a component within the workflow.
• No visibility of the inheritance hierarchy (i.e. what can we expand/collapse).
• No visibility of what you have expanded/collapsed (i.e. where are we in the hierarchy).

Note, for simplicity, this approach groups/collapses all instances of selected families rather than managing this at a per-cycle level. I think this is probably more aligned with expectations, but does represent a minor limitation, e.g. there's no ability to collapse all but one cycle. The ability to expand/collapse specific cycle instances would be a reasonable enhancement.

Design Sketch

Had a quick discussion on this (more to come):

• Can't really think of a valid use case for collapsing all cycles (users would do this in the tree view if they wanted to), so perhaps treat cycles differently (i.e. collapse per-cycle rather than all cycles) and remove from the menus.
• Better expand/collapse icon (obviously).
• The Cylc 7 default of only expanding the cycle point (i.e. show top-level families only) is a reasonable protection for viewing large workflows. We might want to continue with this, or perhaps do something smart (e.g. only collapse families if there are lots of tasks on load).

Check List

• [ ] I have read CONTRIBUTING.md and added my name as a Code Contributor.
• [ ] Contains logically grouped changes (else tidy your branch by rebase).
• [ ] Does not contain off-topic changes (use other PRs for other changes).
• [ ] Applied any dependency changes to both setup.cfg (and conda-environment.yml if present).
• [ ] Tests are included (or explain why tests are not needed).
• [ ] CHANGES.md entry included if this is a change that can affect users
• [ ] Cylc-Doc pull request opened if required at cylc/cylc-doc/pull/XXXX.
• [ ] If this is a bug fix, PR should be raised against the relevant ?.?.x branch.