Allow contacts and custom data to extend subtypes

Extend custom data to work with subtypes
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Change schema to make custom groups be also able to extend subtypes.
Custom group creation process detect subtypes and work for add/update/save actions.

Allow contacts support custom data extending subtypes
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Contact screen should detect/gather/work-with custom data for subtypes associated with the type of contact.
For e.g if a contact of type individual is being added, all custom data extending subtypes extending 'Individual', will be rendered (e.g Parent, Staff ..).
All actions add/update/view/save should be handled.

Custom data extending subtypes should also work as tabs if configured so.