Add occ Commands to allow management of Group Admins - listing, adding, removing

The occ Commands do not currently (NC 20, 21 May 2021) include any concerned with the management of Group Admins.
This would be a welcome addition to the features covered by occ, as this seems to be the only gap in the "Users and Groups" related functionality.

Seeking to have four new commands:-

• Add user as Group Admin to a specified Group
• Remove user's Group Admin status from specified Group
• List all Groups for which a particular user has Group Admin status
• List all the Group Admins for a particular Group

For our installation we would probably only make use of the "List" options, but there would be other installations where the "Add" and "Remove" would be needed.

Terminology

The web interface for NC refers to "Group Admin", however in some of the documentation the term "Subadmin" is also used; from what I can see these are the same thing.

Current situation wrt Group Admins

• Group Admins are shown in the column "Group admin for" on the main web form which displays Users.
• Programmatically the only way they can be accessed is via the "ocs API" commands in the User Provisioning API. Details of commands in this API are below - which is the functionality requested to be added to the occ Commands.

Thanks

Group Admin (aka Subadmin) related commands in User-Provisioning API

• In Section:- Instruction Set for Users

  • Promote user to subadmin
  • Demote user from subadmin
  • Get user’s subadmin groups

• In Section:- Instruction Set for Group

  • Get subadmins of a group

How to use GitHub

• Please use the 👍 reaction to show that you are interested into the same feature.
• Please don't comment if you have no relevant information to add. It's just extra noise for everyone subscribed to this issue.
• Subscribe to receive notifications on status change and new comments.

Start at the occ command entry point and compare existing user and group management commands with the User Provisioning API sections linked in the issue. Done means occ supports adding, removing, and listing Group Admins for users and groups, with behavior consistent with the existing API terminology.