Call SmithyClient destroy from client (#156)

* client destroy method will call SmithyClient destroy by default

* move calling default detroy after other customizations destroy

Author: AllanZhengYP

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/ServiceGenerator.java

@@ -331,6 +331,8 @@ private void generateDestroyMethod() {
                 });
             }
             writer.popState();
+            // Always call destroy() in SmithyClient class. By default, it's optional.
+            writer.write("super.destroy();");
         });
     }
 }