Store the list of properties to retain when a rule is attached to a document

As a records manager, I can guarantee that the list of properties to retain are defined when a rule is attached to a document

AC
In order to prevent a configuration change that would lessen the security of a record, the list of retainable properties should be enforced on the document directly.

When a retention rule is applied to a document, the properties to retain are stored as a part of the document.

If configuration is changed, the configuration applied remains the one that was enforced at the time when the rule was attached to the document.