FR: Read-only administrative users in groups

It would be nice if a Terra user could be added to a Terra Group such that they can see who is in the Group, but not be able to add users. One an envision an administrator who approves group access, but isn't granted the ability to modify the group. It can be very useful for such administrators to still have the ability to see who is in the group.

This would also be useful for setting up an account that is able to programmatically list the contents of the Terra Group, but is not given the ability to make changes to the group.