Implement a rough optgroup-based "Move on Workboard" stacked action
Summary:
Ref T6027. Try this out and see how it feels? Clear issues:
- This definitely shouldn't be at the top.
- You should probably be able to select it multiple times?
- Some of the "which columns show up" rules might need adjustment?
- Diamond marker maybe not great?
Not sure I love this but it doesn't feel terrible...
Test Plan: {F1207891}
Reviewers: chad
Reviewed By: chad
Maniphest Tasks: T6027
Differential Revision: https://secure.phabricator.com/D15638