[ fix ] the test runner for v2.0-joss-submission

[gallais]

Unfortunately we never worried about pinning down the versioning story
and agda makes that quite difficult.

I am hand-writing cabal files for these. We should then port these changes
over to the main branch, with updated bounds to be able to use more modern
versions of GHC & accompanying packages.

• Get the test runner to build & run
  This now works when calling AGDA_EXEC=agda-2.6.4 GHC_EXEC=ghc-9.2.8 make testsuite
• Fix all the tests (probably need the same GHC-pinning & test-specific cabal file rigmarole)
• Document the process
• Use this new approach for the CI

[MatthewDaggitt]

Wow this looks hairy. Thanks so much @gallais! Let me know when we can merge this in...

[gallais]

I'll polish it this afternoon (specifically the part documenting what needs to
be changed after releases / changes in the dependencies) and then will mark
it ready for review.

[gallais]

CI work is hell

Unfortunately did not have time to finish it today. I'm busy tomorrow & then
will be traveling so this may not come to a conclusion before early / mid December.

[gallais]

Nevermind, it looks like continuing to hack while watching Limmy's show did deliver! 🥳

[JacquesCarette]

Hero work! Looks fantastic.

[jamesmckinna]

Heroic refactoring!
Hopefully re-exportable going forward?
And... who knew that a 3pp. placeholder documentation effort would end up consuming so many resources!?
(:sadface:, :facepalm: etc.)

[gallais]

Hopefully re-exportable going forward?

Yes, I tried to design it so that it could be easily upgraded & extended to the new tests
once cherry-picked into master.

consuming so many resources

I think it was a good thunk-forcing function for stuff we should have done a while ago
(in this instance actually figuring out how to reliably build these examples with external
dependencies).

[jamesmckinna]

Re: resources. I'd been thinking of the human ones, much more than the machine ones, but yes... ;-)