Issue #2978747: Hide field groups when all children hidden via js states

Closes #2978747

Add field group Javascript States testing to highlight the current issue.

Fixes the issue by:

• Adding a css class to all group children on forms to make it easier to identify group children in js
• Adding state:visible event listener and associated methods to check if an element being hidden/shown is a field group child, and if it is, determines if its parent group/s are empty or not empty and triggers either a field_group:group_empty or field_group:group_not_empty event.
• Adding field_group:group_empty & field_group:group_not_empty listeners to specific group type js files to handle hiding and showing the group element/s.