ci: Add various CI tools

[LecrisUT]

Here are some of the CI tools for #35.

It seems you need to configure the repository to request approval or specify how GH action should run. Can check run in my fork

Missing:

• ReadTheDocs: need instructions on how to build with ford
• Ctests: these are not yet implemented I'll leave it to you to check them

[LecrisUT]

This one might be worth to merge normally because of a9cc38192bd452c7822801d0beebdd3a6c87268d, otherwise the git blame might be a bit confusing

[zerothi]

There are many things here, and quite a bit of things I don't want in it ;)

I'll have to go through some of the things to clean this up.

In any case, thanks for your very big contribution!

[LecrisUT]

These are copied from my other projects. I have separated them by commits so we can discuss them individually.