New Function: establishCuratedGroup

Add a new function that adds users to a group as org_admin and also sets the group to accept contributions from group admins only.

Inputs: existing groupID and a list of users
Uses: undocumented addUser operation
Returns: nothing (or report?)

Start by locating the existing group-administration entry points and the undocumented addUser operation. Confirm how groupID and the user list are represented, how admin-only contributions are configured, and whether the function should return nothing or a report; done means the requested group membership and contribution restriction are applied consistently.

Written by the indexing model from the issue text.