Validate menu item fields (links, projects, dashboards, applications, forms, etc)
Ref T12128. This adds validation to menu items.
This feels a touch flimsy-ish (kind of copy/paste heavy?) but maybe it can be cleaned up a bit once some similar lightweight modular item types (build steps in Harbormaster, blueprints in Drydock) convert.
- Tried to create each item with errors (no dashboard, no project, etc). Got appropriate form errors.
- Created valid items of each type.
Reviewed By: chad
Maniphest Tasks: T12128
Differential Revision: https://secure.phabricator.com/D17235