The assignment of the user group to user is inconsistently logging to audit

Currently the assignment of user group to user is logged in two different ways:

• If user group assigned to user using User group API, the following details are logged:

usergroup.users[7]: Added
usergroup.users[7].id: 7
usergroup.users[7].userid: 3

• If user group assigned to user using User API, the following details are logged:

user.usrgrps[6]: Added
user.usrgrps[6].id: 6
user.usrgrps[6].usrgrpid: 14

To make this assignment consistent with assignments of other API objects we should to log this assignment as the change in User API object independently from the approach of how it was done.