Update rules:

CS8604 (PROD) => changed from warning to error
CA2012 (TEST) => changed from error to warning

Author: xaviersolau

src/libs/SoloX.CodeQuality.Prod/resources/style.cs.compiler.cs.editorconfig

@@ -10,3 +10,6 @@ dotnet_diagnostic.CS0168.severity = error
 
 # CS8603: Possible null reference return.
 dotnet_diagnostic.CS8603.severity = error
+
+# CS8604 Possible null reference argument.
+dotnet_diagnostic.CS8604.severity = error

src/libs/SoloX.CodeQuality.Test/resources/style.cs.compiler.ca.editorconfig

@@ -323,7 +323,7 @@ dotnet_diagnostic.CA2009.severity = error
 dotnet_diagnostic.CA2011.severity = error
 
 # CA2012: Utilisez correctement ValueTasks
-dotnet_diagnostic.CA2012.severity = error
+dotnet_diagnostic.CA2012.severity = warning
 
 # CA2013: Ne pas utiliser ReferenceEquals avec des types valeur
 dotnet_diagnostic.CA2013.severity = error