Qualify the name of the CharSet type for LibraryImport downlevel/fallback usages (#118460)

Co-authored-by: Copilot <[email protected]>

Author: jkoritzinsky

src/libraries/System.Runtime.InteropServices/gen/DownlevelLibraryImportGenerator/DownlevelLibraryImportGenerator.cs

@@ -375,7 +375,7 @@ private static AttributeSyntax CreateForwarderDllImport(LibraryImportData target
                 NameEqualsSyntax name = NameEquals(nameof(DllImportAttribute.CharSet));
                 ExpressionSyntax value = MemberAccessExpression(
                     SyntaxKind.SimpleMemberAccessExpression,
-                    ParseTypeName(typeof(CharSet).FullName),
+                    AliasQualifiedName("global", IdentifierName(typeof(CharSet).FullName)),
                     IdentifierName(nameof(CharSet.Unicode)));
                 newAttributeArgs.Add(AttributeArgument(name, null, value));
             }

src/libraries/System.Runtime.InteropServices/gen/LibraryImportGenerator/LibraryImportGenerator.cs

@@ -533,7 +533,7 @@ static ExpressionSyntax CreateEnumExpressionSyntax<T>(T value) where T : Enum
             {
                 return MemberAccessExpression(
                     SyntaxKind.SimpleMemberAccessExpression,
-                    IdentifierName(typeof(T).FullName),
+                    AliasQualifiedName("global", IdentifierName(typeof(T).FullName)),
                     IdentifierName(value.ToString()));
             }
         }