Update valid values for /warn compiler option (#46989)
Update valid values for /warn compiler option (#46989)


bartdesmet/roslyn,heejaechang/roslyn,sharwell/roslyn,jasonmalinowski/roslyn,wvdd007/roslyn,tannergooding/roslyn,mavasani/roslyn,panopticoncentral/roslyn,weltkante/roslyn,dotnet/roslyn,eriawan/roslyn,AlekseyTs/roslyn,KirillOsenkov/roslyn,shyamnamboodiripad/roslyn,physhi/roslyn,ErikSchierboom/roslyn,KirillOsenkov/roslyn,shyamnamboodiripad/roslyn,stephentoub/roslyn,dotnet/roslyn,sharwell/roslyn,panopticoncentral/roslyn,mavasani/roslyn,CyrusNajmabadi/roslyn,bartdesmet/roslyn,KirillOsenkov/roslyn,weltkante/roslyn,eriawan/roslyn,heejaechang/roslyn,KevinRansom/roslyn,shyamnamboodiripad/roslyn,eriawan/roslyn,gafter/roslyn,ErikSchierboom/roslyn,ErikSchierboom/roslyn,tmat/roslyn,jasonmalinowski/roslyn,AlekseyTs/roslyn,weltkante/roslyn,diryboy/roslyn,physhi/roslyn,diryboy/roslyn,KevinRansom/roslyn,wvdd007/roslyn,AlekseyTs/roslyn,diryboy/roslyn,AmadeusW/roslyn,physhi/roslyn,CyrusNajmabadi/roslyn,tmat/roslyn,gafter/roslyn,sharwell/roslyn,heejaechang/roslyn,panopticoncentral/roslyn,jasonmalinowski/roslyn,mgoertz-msft/roslyn,wvdd007/roslyn,mgoertz-msft/roslyn,tannergooding/roslyn,dotnet/roslyn,KevinRansom/roslyn,stephentoub/roslyn,mgoertz-msft/roslyn,mavasani/roslyn,stephentoub/roslyn,AmadeusW/roslyn,tannergooding/roslyn,bartdesmet/roslyn,AmadeusW/roslyn,tmat/roslyn,gafter/roslyn,CyrusNajmabadi/roslyn