Hi Guix!

I have the attached file that build Scala, although it's not
bootstrapped at all. It contains %binary-scala, a few dependencies of
Scala we haven't packaged yet, and the final scala, built from
%binary-scala, without sbt (which requires Scala too).

Since I've tried and failed to bootstrap Scala for so long, I think
it's time to give up. I can't always create miracles.

If this is acceptable, I will send actual patches later, and rework the
sbt package I had around 2018 (I managed to build it with a Scala
compiler, without a pre-existing sbt).