Sync client-side poll validation with server-side validation
Sync client-side poll validation with server-side validation

`PollManager` marks an empty question field as empty if poll options are given, while `WCF.Poll.Management` aborted validation once the question field is empty, no matter whether options are given or not.

WoltLab/WCF,Cyperghost/WCF,WoltLab/WCF,WoltLab/WCF,WoltLab/WCF,Cyperghost/WCF,SoftCreatR/WCF,SoftCreatR/WCF,Cyperghost/WCF,SoftCreatR/WCF,Cyperghost/WCF,SoftCreatR/WCF,Cyperghost/WCF