src: add LoadEnvironment() variant taking a string

Allow passing a string as the main module rather than using
the callback variant.

PR-URL: https://github.com/nodejs/node/pull/30467
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>

src/node_native_module_env.h

@@ -29,6 +29,7 @@ class NativeModuleEnv {
   // Returns config.gypi as a JSON string
   static v8::Local<v8::String> GetConfigString(v8::Isolate* isolate);
   static bool Exists(const char* id);
+  static bool Add(const char* id, const UnionBytes& source);
 
   // Loads data into NativeModuleLoader::.instance.code_cache_
   // Generated by mkcodecache as node_code_cache.cc when