Revert "fix: stop adding serde middleware repeatedly (smithy-lang#259)"

This reverts commit c57cca3.

client instance, the command still consumes the configuration of
the previous client interface. This issue is resolved by allowing
adding middleware to the stack without throwing error. So smithy-lang#259 is
no longer needed.

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

@@ -104,7 +104,6 @@ public void run() {
         writer.writeShapeDocs(operation);
         writer.openBlock("export class $L extends $$Command<$T, $T, $L> {", "}", name, inputType, outputType,
                 configType, () -> {
-            writer.write("private resolved = false;");
 
             // Section for adding custom command properties.
             writer.write("// Start section: $L", COMMAND_PROPERTIES_SECTION);
@@ -146,15 +145,11 @@ private void generateCommandMiddlewareResolver(String configType) {
                 .write("options?: $T", applicationProtocol.getOptionsType())
                 .dedent();
         writer.openBlock("): Handler<$T, $T> {", "}", inputType, outputType, () -> {
-            writer.openBlock("if (!this.resolved) {", "}", () -> {
-                // Add serialization and deserialization plugin.
-                writer.write("this.middlewareStack.use($T(configuration, this.serialize, this.deserialize));", serde);
+            // Add serialization and deserialization plugin.
+            writer.write("this.middlewareStack.use($T(configuration, this.serialize, this.deserialize));", serde);
 
-                // Add customizations.
-                addCommandSpecificPlugins();
-
-                writer.write("this.resolved = true;");
-            });
+            // Add customizations.
+            addCommandSpecificPlugins();
 
             // Resolve the middleware stack.
             writer.write("\nconst stack = clientStack.concat(this.middlewareStack);\n");

smithy-typescript-codegen/src/test/java/software/amazon/smithy/typescript/codegen/CommandGeneratorTest.java

@@ -18,10 +18,7 @@ public void addsCommandSpecificPlugins() {
                 "    configuration: ExampleClientResolvedConfig,\n" +
                 "    options?: __HttpHandlerOptions\n" +
                 "  ): Handler<GetFooCommandInput, GetFooCommandOutput> {\n" +
-                "    if (!this.resolved) {\n" +
-                "      this.middlewareStack.use(getSerdePlugin(configuration, this.serialize, this.deserialize));\n" +
-                "      this.resolved = true;\n" +
-                "    }\n" +
+                "    this.middlewareStack.use(getSerdePlugin(configuration, this.serialize, this.deserialize));\n" +
                 "\n" +
                 "    const stack = clientStack.concat(this.middlewareStack);");
     }