Add julia 1.9.3

This is based on julia 1.8.3 with several changes to fix linking and make sure tests pass.

I'm creating a MR to give some visibility and provide a place to ask for review/prepare for a proper patch upstream: the clear goal is to purely revert this commit in the near future once it's upstream.

The code has been guix-styled, but all the concerns raised by guix lint have not been addressed.

I'm merging right away so that users can benefit from it right now.