Enhance error messages for the new Groups/Users page

Problem Definition

Right now when a problem happens while adding a new user to a group the UI only displays:

The same goes when trying to add a user to a group from the user profile while in the new UI.

Looking at the post error through the developer panel of the browser we can clearly see the root cause of the problem:

{"key":"badRequest","context":{"message":"Unable to add users to groups without exceeding licence"}}

The error was handled when trying to add the user to the group through the old user profile:

Suggested Solution

Enhance the error messages for the new groups/users UI to let the user aware of why the group addition didn't work.

Notes

This message "Something went wrong" also applies for cases where a site-admin is inviting new users and suggesting changes to users account.