[Flight] Support Async Modules in Turbopack Server References (#34531)

Seems like this was missed in
https://github.com/facebook/react/pull/31313

packages/react-server-dom-turbopack/src/client/ReactFlightClientConfigBundlerTurbopack.js

@@ -132,7 +132,19 @@ export function resolveServerReference<T>(
       );
     }
   }
-  // TODO: This needs to return async: true if it's an async module.
+  if (resolvedModuleData.async) {
+    // If the module is marked as async in a Client Reference, we don't actually care.
+    // What matters is whether the consumer wants to unwrap it or not.
+    // For Server References, it is different because the consumer is completely internal
+    // to the bundler. So instead of passing it to each reference we can mark it in the
+    // manifest.
+    return [
+      resolvedModuleData.id,
+      resolvedModuleData.chunks,
+      name,
+      1 /* async */,
+    ];
+  }
   return [resolvedModuleData.id, resolvedModuleData.chunks, name];
 }