Wrap up Nix Build for Node Wrapper

[mikiquantum]

This PR continues the work from @asymmetric (Thanks!) in this PR

One important thing to note, is that the build process skips building the WASM, this means that the binary and/or docker image needs to use an external spec to work. In later iterations we will add this support.

At the moment images are tagged with a nix-do-not-use suffix until we verify all is fine on production nodes.

A following PR, once we have WASM builds, will cover cleaning up and remove duplication of RUST_TOOLCHAIN in github actions.

[gpmayorga]

I think we should either remove the Dockerfile(s) and/or rename them and/or move them to a different directory to avoid confusion, as I understand it this replaces the Dockerfile process completely?

[mikiquantum]

@gpmayorga the idea is to try this image out in live networks first and then replace all the docker code later. The other reason why we do not remove all that here, is because this binary and docker images doesnt build the wasm, so we cannot use that for our non-live environments. Once we fix that (will create a PR soon) we can do the cleanup.
In any case, I would like to get this merged independently.

[mikiquantum]

@branan & @gpmayorga please have another look and give a thumbsup or ask more questions, so we can get this one in.

[branan]

I don't really know Nix well enough to judge this properly, so if everybody else is happy I am. No need to block on me

[gpmayorga]

Looks good to me. I like the idea of reading settings from file within the Nix code. I added a question but nothing critical, approving the merge from my end