[POC] Adopt a third party tool to handle cloudbeat async pipeline

## Motivation
Today in cloudbeat, we have our own custom implementation for handling asynchronous flow.
In posture flavor, we are using `Step`, a thin generic function to support a multilayer of asynchronous pipelines implemented over go channels.
In vulnerability flavor, we are using the `worker`, a main component that syncs between all the async providers, this implementation forces all the providers to be channels aware and focused on the pipeline instead of the business logic.

## Proposition: [RxGo](https://github.com/ReactiveX/RxGo)
A well-tested library to handle async pipeline of events, that will allow us to focus on the business logic implementation and go forward without the concern synchronisation bugs.
Maybe as a further step, it can replace the `pipeline` package entirely.
RxGo has 4.5K stars, and the organization is also popular among other coding languages.

### Definition of done
- [ ] A POC to check if the library fits our requirements
- [ ] A summary of the pros and cons of using it
- [ ] Wrap a single async flow in cloudbeat (vulnerability scanning for example) with the selected third party tool