fix external module (#7961)

### Description

With `is_esm: true` `module` is not available.

### Testing Instructions

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Closes PACK-2961

crates/turbopack-ecmascript/src/references/external_module.rs

@@ -89,7 +89,7 @@ impl CachedExternalModule {
         Ok(EcmascriptModuleContent {
             inner_code: code.build(),
             source_map: None,
-            is_esm: true,
+            is_esm: self.external_type != CachedExternalType::CommonJs,
         }
         .cell())
     }