Add attachments in the Retention Management addon

User story

As a record manager, I want to apply a retention rule or a legal hold to a document with attachment(s), so that I can use both attachments and retention features on my Nuxeo instance.

Description

The goal is to make the Retention add-on compliant with the attachment feature. 

In this version, attachments are NOT part of the record but more a business metadata that can be deleted or updated.

(In a more long term version, attachments could be added as part of the record).

Acceptance criteria

• As a granted user, I can add or delete attachment(s) to a document in a Nuxeo instance with Retention add-on
• As a record manager, I can apply a retention rule to a document with a main file and attachment(s),
• As a record manager, I can apply a legal hold to a document with a main file and attachment(s),
• As a granted user, when a document is under retention or legal hold, I can delete the attachment(s) files
• As a granted user, when a document is under retention or legal hold, I can add attachment(s) files