Add CI stage to build against current Vulkan-Docs main branch

[oddhack]

Per #1760, could you add a CI stage that pulls the current Vulkan-Docs main branch, generates whatever artifacts you need from that, and builds / compiles Vulkan-Hpp based on that? Basically the counterpart of the vulkan hpp-generate / hpp-compile stages. That would hopefully catch new Vulkan-Hpp issues before they affect all new runs of the CI stages in the vulkan repos.

[asuessenbach]

That sounds like a good idea.
But in view of the error pattern and its solution, I would assume that it's a compiler specific issue. So maybe it's a better move to add the compiler you're using to our CI.
I see, your builds run on "ubuntu-latest", which is 22.04. But I can't identify the compiler version(s) used. Can you help me with that?

[oddhack]

It doesn't really matter what the runs on is since everything is packaged in a Docker container running Debian - at present

gcc version 10.2.1 20210110 (Debian 10.2.1-6)