Move "Form action" widget types to the "advanced" widget types section

The "Form Action(s)" widget types are only interesting in combination with the advanced "Layout" widget type so they should be presented next to each other.
The other interesting use case is incremental layouts configuration (with summary categories for instance), so this should wait for the feature to be available in Studio in a user-friendly way (see NXS-1824 for related issues)

The "Toolbar Action(s)" widget types are more likely to be used within tabs.