Fire OnUserRemoveFromGroup event from user update window

[dannyarty]

Feature request

Summary

Modx 3.0.4, PHP 7.4
I created a simple plugin and registered it to OnUserRemoveFromGroup event. When I was trying to remove user from a group on the User Update page, the event was not triggered. It fires only when a user is removed from a group while editing it in the ACL context.

Why is it needed?

Most users, especially average site managers, don't use ACL context. Adding and removing user from groups, usually made on User Update window. So it would be great if OnUserRemoveFromGroup event would fire in that case, as OnUserAddToGroup does.

Suggested solution(s)

Compare current user groups and the new ones in the setUserGroups method, which is declared in user update processor.