Set __isLogin if a logged-in user lacks `admin.general.canUseAcp`
Set __isLogin if a logged-in user lacks `admin.general.canUseAcp`

Resolves #4307

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