feat(codegen): add mutateClientPlugins() integration hook

Author: Steven Yuan

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

@@ -102,6 +102,11 @@ public TypeScriptCodegenContext createContext(CreateContextDirective<TypeScriptS
             });
         });
 
+        directive.integrations().forEach(integration -> {
+            LOGGER.info(() -> "Mutating plugins from TypeScriptIntegration: " + integration.getClass().getName());
+            integration.mutateClientPlugins(runtimePlugins);
+        });
+
         ProtocolGenerator protocolGenerator = resolveProtocolGenerator(
                 directive.integrations(),
                 directive.model(),

smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/TypeScriptIntegration.java

@@ -64,6 +64,13 @@ default List<RuntimeClientPlugin> getClientPlugins() {
         return Collections.emptyList();
     }
 
+    /**
+     * Mutates in place the loaded list of plugins to apply to the generated client.
+     */
+    default void mutateClientPlugins(List<RuntimeClientPlugin> plugins) {
+        // defaults to no mutation
+    }
+
     /**
      * Gets a list of protocol generators to register.
      *