Create seperate permission for adding field inheritance

I discovered this problem in the recurring_events module:
https://www.drupal.org/project/recurring_events/issues/3357979 🐛 Add Instance Button does not respect Inheritance Active

As it is right now, field_inheritance only has a single permission.
This means that when you add new instances that should use field inheritance, it does not work, unless you have that permission.

This patch adds a separate permission for also being allowed to actually use field inheritance.

I've also added a details wrapper around the fields, to make the admin experience a bit more friendly.

Important - should we migrate existing users that have the original permission, to also have this permission?