Record management - Retention policy application rules

User story

• As a record manager, I want that only 1 retention policy can be applied to a document, so that I can guarantee that no one can change the retention policy applied to a document by adding a new one
• As a record manager, I want that the changes made on a retention policy are not retroactive in order to not impact the documents on which the retention policy has been applied before the changes, so that I can guarantee that no one can change the retention policy applied to a document (apart by using the override retention feature, cf. +https://jira.nuxeo.com/browse/NXP-27383+ )

Acceptance criteria

• I can’t apply a retention policy to a document already linked to another retention policy, even by using API
• I can’t apply again a retention policy to a document already linked to the retention policy, even by using API
• After I changed the retention period of a retention policy:
  • The expiration date is calculated based on the new retention period when I apply the retention policy to a document
  • The expiration date of the documents previously linked to the retention policy doesn’t changed
• After I changed the retention period starting point of a retention policy:
  • The expiration date is calculated based on the new retention starting point when I apply the retention policy to a document
  • The expiration date of the documents previously linked to the retention policy doesn’t changed