Separate Team-Folders and Group-Folders again

Team folders / Group folders proposal

We separate team- and groupfolders again.

Group folders

The current team folders are renamed back to group folders. They can still freely be created and managed by admins.

• Admins can create and manage from the section "Group folders" in the admin settings
• All functionality like quota, ACL's, etc. stay the same
• Both groups and teams can be given permissions to them

Team folders

Team-folders become the main storage for teams, both for files and for connected apps.

• 1:1 relation to a team (#2643, #2734)
• Automatically created upon team creation (#2661)
• Auto-creation can be opted out of when crating a team (#2744), though this option is hidden in an "advanced" tab to encourage the use of teams with team-folders.
• Contain a .system folder for apps. All collaborative apps are encouraged to move their user-data into this directory in the effort of moving apps to team-ownership. (#2634, #2644)

Quota

When creating a team-folder, the quota for this folder is set according to the users membership in groups. In a later step, these groups should also be used to calculate current quota usage.

• https://github.com/nextcloud/circles/issues/2895

Start by reviewing the current team-folder implementation and the linked issues #2643, #2734, #2661, #2744, #2634, #2644, and #2895. Map the proposed separation of group folders and team folders, including permissions, automatic creation, app storage, and quota behavior. Done means the proposal's relationships and lifecycle rules are implemented consistently.