Prevent admins from editing return items that have a processed exchange

Show return authorization return item preferred_reimbursement_type

When item isn't editable

Fixes #5651
Added reimbursed scope.

Fixes #5653
Update default same product rule

Changes:

- allows the SameProduct rule to exchange an item for the same item
- filters out out-of-stock variants for the SameProduct rule

Fixes #5652
fix api orders_controller_spec

Zipcode validation was failing in our fork because we have extra validation and the country didn't match up in these.
Also, remove some unused rspec address definitions.

fixes #5654