{
// required
assignment_id: Id;
meeting_user_id: Id;
}Creates an assignment candidate for the assignment. It is forbidden, if the assignment phase is finished.
If the meeting_user_id is equal the meeting_user with the request user id, the user needs assignment.can_nominate_self, else the user needs assignment.can_nominate_other.
In both cases: If the assignment phase is voting, the request user also needs assignment.can_manage.