Add parent type reference to opaque types.

Author: pluskal

shared/src/main/scala/io/kaitai/struct/languages/CSharpAsyncCompiler.scala

@@ -384,7 +384,7 @@ class CSharpAsyncCompiler(val typeProvider: ClassTypeProvider, config: RuntimeCo
           }
           s", $parent, ${privateMemberName(RootIdentifier)}$addEndian"
         }
-        s"await (new ${types2class(t.name)}($addParams$io$addArgs)).ReadAsync()"
+        s"await (new ${types2class(t.name)}(this, $addParams$io$addArgs)).ReadAsync()"
     }
   }