tree: auto-collapse final-complete tasks

[oliver-sanders]

Automatically collapse groups (aka cycles/families) where all of the visible tasks have a final status and have completed all required task outputs.

This feature was requested from a rose-stem context where it would be rather useful, keeping the tree view focused on waiting/failed tasks whilst keeping succeeded tasks available for inspection.

The best alternative to this that is currently possible is to filter out succeeded tasks via the dropdown. Note this is currently a little clumsy due to the lack an invert selection button and makes it harder to inspect succeeded tasks if that is desirable.

Question: Makes sense? Any other ideas to fulfil the requirement.

Note, this will require final-complete/final-incomplete status in the schema, see also final-incomplete events - cylc/cylc-flow#4957