Guix package: Switch to asdf-build-system to enable support for Nyxt extension Guix packages

[Ambrevar]

Currently Nyxt 2.2.4 packaged for Guix uses the gnu-build-system, which does not expose the Nyxt "systems" to ASDF.

To fix this, we should switch to the asdf-build-system, which would require only a few changes to the recipe.

Then the nx-router recipe could be written like any other SBCL packages, with nyxt as input.

[Ambrevar]

CC @jgarte

[jgarte]

Hi, somehow I just saw this now because I was hanging out in #tropin on libera.chat and someone mentioned nyxt extension's and this issue ;()

[jgarte]

What's the status on this?

Looks like it wouldn't be too much work to put together.

[Ambrevar]

Nothing was fixed yet, help is welcome! Shouldn't be too much work, but the executable generation needs to be done manually I believe. We could check how StumpWM is built.

[aadcg]

Somewhat related to #131.