Remove support for comments, assets, permissions and folder root selection from external repositories

• Type: Story
• Status: Closed
• Priority: Minor
• Resolution: Completed
• Affects Version/s: None
• Fix Version/s: 7.0.0 DXP FP43, 7.0.6 CE GA7, 7.0.0 DXP SP8, 7.0.X, 7.1.X, Master
• Component/s: External Document Repositories
• Labels:
  • liferay-digital-enterprise-70-sp8
  • liferay-fixpack-de-43-7010
• Branch Version/s:
  7.0.x
• Backported to Branch:
  Committed
• Priority Level: Low
• Sprint: 01_The Phamton, 02_Superman, Wheeljack, Prowl, Jazz, 04_Matter_Eater_Lad
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/51838

External repositories aren't supposed to have some features (like comments, assets, etc.), but due to some oversights in different parts of the product, they're partially supported.

In this story we'll remove all these "accidental" features from external repositories:

• Comments
• Assets
• Permissions
• Ability so set external folders as root folders in D&M

There are different reasons why we cannot properly implement these features:

1. In the case of D&M root folders, Comments and Assets, there's no permanent data stored in the DB that can be used to attach this information (as RepositoryEntry is not really persisted).
2. Permissions should be set in the guest repository (Alfresco, Sharepoint, etc.) not in Liferay.

Note that for (1) we cannot simply store the information in the database. Elements can be removed or moved around in the backend repository at any time without Liferay noticing any of this. This would eventually lead to the RepositoryEntry table being filled with lots of invalid data, which also would be very expensive to purge.