Disable new elements added to a custom composite when already in use

Problem/Motivation

Currently, when a new element is added into a custom composite, it shows up in all the form instances where the composite is in use.

Steps to reproduce

1. Create a contact details composite with first name and last name.
2. Add the composite to a webform.
3. Update the composite to include middle name.

It will automatically show up on the form.

Proposed resolution

When new elements are added to a composite that is in use - the element must be disabled.

Remaining tasks

User interface changes

API changes

Data model changes