Move the nullable disable warning region to the Type instead of the base CachedSymbol entity

Author: tamasvajk

csharp/extractor/Semmle.Extraction.CSharp/Entities/CachedSymbol.cs

@@ -11,12 +11,10 @@ namespace Semmle.Extraction.CSharp.Entities
 {
     internal abstract class CachedSymbol<T> : CachedEntity<T> where T : class, ISymbol
     {
-#nullable disable warnings
-        protected CachedSymbol(Context cx, T? init)
+        protected CachedSymbol(Context cx, T init)
             : base(cx, init)
         {
         }
-#nullable restore warnings
 
         public virtual Type? ContainingType => Symbol.ContainingType != null ? Type.Create(Context, Symbol.ContainingType) : null;
 

csharp/extractor/Semmle.Extraction.CSharp/Entities/Types/Type.cs

@@ -10,9 +10,10 @@ namespace Semmle.Extraction.CSharp.Entities
 {
     internal abstract class Type : CachedSymbol<ITypeSymbol>
     {
+#nullable disable warnings
         protected Type(Context cx, ITypeSymbol? init)
             : base(cx, init) { }
-
+#nullable restore warnings
 
         public override bool NeedsPopulation =>
             base.NeedsPopulation || Symbol.TypeKind == TypeKind.Dynamic || Symbol.TypeKind == TypeKind.TypeParameter;