Add mode for using the required versions of GAP and needed packages

[wilfwilson]

A GAP package requires a minimum version of GAP, and it typically needs several other packages, with specified minimum required versions.

For example, the recog package currently says that it requires (at least) GAP 4.9, AtlasRep 1.4.0, FactInt 1.5.2, Forms 1.2, genss 1.3, and Orb 3.4.

In my experience, it is often not noticed when these numbers need to be updated. Therefore, I think it would be nice in the CI scripts to have a way of automatically installing only the required version of GAP, and/or the required versions of the needed packages. This way, one would very quickly notice when the required versions should be updated.

I do this in a bespoke way for the Semigroups and Digraphs CI tests. I'm not sure how to integrate this with the setup here, but I'll have a think.

Perhaps this is a crazy idea. If you think so, it would be nice to know that as well, so that I can stop maintaining the system I have on Semigroups and Digraphs.

[wilfwilson]

If I ever take this idea forward, I should integrate/coordinate it properly with the https://github.com/gap-actions stuff; see gap-actions/setup-gap#28.