fix(runtime-core): expose ssrUtils in esm-bundler build

this is necessary for worker environments where Vue needs to be
bundled (instead of using cjs build via Node.js require)

fix #4199

packages/runtime-core/src/index.ts

@@ -313,7 +313,9 @@ const _ssrUtils = {
  * SSR utils for \@vue/server-renderer. Only exposed in cjs builds.
  * @internal
  */
-export const ssrUtils = (__NODE_JS__ ? _ssrUtils : null) as typeof _ssrUtils
+export const ssrUtils = (
+  __NODE_JS__ || __ESM_BUNDLER__ ? _ssrUtils : null
+) as typeof _ssrUtils
 
 // 2.x COMPAT ------------------------------------------------------------------