module: unflag Top-Level Await

This unflags Top-Level await so it can be used by default in the module
goal. This is accomplished by manually setting the
--harmony-top-level-await flag. We are allowing this as a one of
approval based on circumstances. It is not a precedent that future
harmony features will be manually enabled.

Refs: https://github.com/nodejs/node/issues/34551

PR-URL: https://github.com/nodejs/node/pull/34558
Reviewed-By: Mary Marchini <oss@mmarchini.me>
Reviewed-By: Zeyu Yang <himself65@outlook.com>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Shelley Vohr <codebytere@gmail.com>

tools/code_cache/mkcodecache.cc

@@ -27,6 +27,7 @@ int main(int argc, char* argv[]) {
 #endif  // _WIN32
 
   v8::V8::SetFlagsFromString("--random_seed=42");
+  v8::V8::SetFlagsFromString("--harmony-top-level-await");
 
   if (argc < 2) {
     std::cerr << "Usage: " << argv[0] << " <path/to/output.cc>\n";