Create a Go bootstrap project

The current situation is that we build Go 1.4 in the go project, just to build the latest version and then we drop it.

A few months ago I've suggested to create a go-bootstrap project with Go 1.4 to avoid building it and dropping it each time we update Go.

With 1.20, things have become worse: 1.20 needs at least 1.17.13 to build.

So, it might be the time to create the bootstrap project to compile 1.19.5 (which is currently the latest from 1.19), and then use it to bootstrap following versions. With this we should be okay for a couple of years, but their new plan is to bump the bootstrapping toolchain every year.