ui: workflow builder iteration

[psychedelicious]

Summary

I implemented these kinda-unrelated changes as I encountered them and didn't create a separate branch, so they are bundled up here. Some cross-pollination w/ the other changes, not gonna worry about splitting them.

• Fix: Model fields that reference nonexistent models weren't reset during workflow loading.
• Fix: After loading a workflow, the first click in the editor resets the zoom.
• Fix: Node title cursor is 'text' - should be 'grab'.
• Chore: Update vitest's UI related packages, fixing a version mismatch taht prevented the test UI dashboard from loading.

Builder changes.

• Refactor: Use root container instead of non-container list for form root, substantially simplifying internal logic. Only tradeoff is a small amount of special handling needed in the UI for the for the root container (e.g. it cannot be deleted and other elements cannot be dragged outside of it).
  ❗ This is a breaking change. Workflows saved in the alpha will no longer load, and users who have a WIP form will get a fatal error and need to click Reset Web UI to fix it. ❗
• Tidy: Organize a lot of builder files.
• Docs: Document the builder utils and hooks. Components still lack comments.
• Feat: When adding an element, the parent id for the new is now required.
• Tests: Add test coverage for form tree manipulation and other utilities. Caught a couple minor issues!

Related Issues / Discussions

Closes #7648

QA Instructions

The change to the data structure for the form has indirectly caused a styling issue w/ the form. I will fix this in a followup.

The form root is now a container, so there's one extra box in the edit view. You cannot delete the root. It'll make sense when you try it.

Besides that, the functionality should be the same.

A good chunk of the code changes are to the lock file.

Merge Plan

n/a

Checklist

• The PR has a short but descriptive title, suitable for a changelog
• Tests added / updated (if applicable)
• Documentation added / updated (if applicable)
• Updated What's New copy (if doing a release after this PR)

[hipsterusername]

New Workflows, I hardly knew ye.