RSC: Make RWJS_ENV etc available on the server during runtime

[Tobbe]

1. First thing we need to realize here is that Redwood framework files that use global environment variables like RWJS_API_URL or __REDWOOD__APP_TITLE will still have those unresolved after building the framework.
2. They will also still be unresolved after building the RW app itself, because building the app doesn't touch the already built FW files in node_modules.
3. This means they need to be resolved during runtime.
4. For yarn rw dev we set those global environment variables in the dev server config
5. For yarn rw serve we call registerFwGlobals() to register them
6. When serving an RSC enabled app we spin up a worker thread to handle rendering server components to flight format.
7. The worker thread runs in its own thread and does not share global variables with the main server process, so we need to also register the global variables for the worker.