Fixed introspection utils to support that IsRepeatable is not being specified on directives (#3629)

Author: nloum

src/HotChocolate/Utilities/src/Utilities.Introspection/IntrospectionDeserializer.cs

@@ -261,7 +261,7 @@ private static DirectiveDefinitionNode CreateDirectiveDefinition(
                 null,
                 new NameNode(directive.Name),
                 CreateDescription(directive.Description),
-                directive.IsRepeatable,
+                directive.IsRepeatable ?? false,
                 CreateInputValues(directive.Args),
                 locations
             );

src/HotChocolate/Utilities/src/Utilities.Introspection/Models/Directive.cs

@@ -11,7 +11,7 @@ internal class Directive
         public string Description { get; set; }
         public ICollection<InputField> Args { get; set; }
         public ICollection<string> Locations { get; set; }
-        public bool IsRepeatable { get; set; }
+        public bool? IsRepeatable { get; set; }
         public bool OnOperation { get; set; }
         public bool OnFragment { get; set; }
         public bool OnField { get; set; }