`process.on` is not implemented

I'd like to [gracefully shutdown my lambda](https://github.com/aws-samples/graceful-shutdown-with-aws-lambda/tree/main/nodejs-demo)

However, looks like LLRT has no `process.on('SIGTERM', ...` implemented yet
```[tasklist]
### Tasks
- [ ] implement process.on
- [ ] emit SIGTERM event
```
