k6 extension: New experimental HTTP API

[codebien]

Exploring problems and solutions for #2311 has shown us that trying to fix all the problems in the old API would require compromises that wouldn't solve the root cause of the issue.

To that end, we have decided to explore solutions for this and other HTTP-related issues in a new k6 extension. This will be an implementation of a new HTTP API, and will require changes in several core parts of k6.

We've come up with a design document for this work, with some initial ideas that would address most of these issues. The design is still very much in flux, and will likely change as the work progresses.

### Task list
- [ ] https://github.com/grafana/k6/issues/3038
- [ ] https://github.com/grafana/k6/issues/1011

[saniyar-dev]

Hi. I assume that new-http api is not in default k6 binary. How can I build/download a proper binary which includes this api?

[codebien]

Hey @saniyar-dev, as you can see https://github.com/grafana/k6/issues/3038 is still open, which means there isn't yet an implementation available for the new HTTP API.

[olegbespalov]

As we agreed during a meeting, we need to ensure that at some point a new HTTP module covers a case from https://github.com/grafana/k6/issues/1169