Fire group events in `UserInfo::updateGroups()`

Fire on_user_enter_group and on_user_exit_group in
`UserInfo::updateGroups()`

`UserInfo::updateGroups()` does not call `User::exitGroup()` and
`User::enterGroup()` and instead used single SQL `DELETE`.

- Fire group events for each group removed or added

http://www.concrete5.org/developers/bugs/5-6-2-1/on-user-exit-group-trigger