Preliminary json support for GPU detection

[Aiden2244]

Towards archspec #247

Encodes relationship between GPU vendor PCI codes and human-readable names, as well as the PCI classes to search for sysfs GPU detection.

[Aiden2244]

@alalazo do you have a moment for a quick review on this? This would unblock the main archspec PR.

[alalazo]

@Aiden2244 In which way is this blocked? Can't you update the JSON file here as you work towards refining archspec/archspec#247 ?

In my opinion it's the archspec PR that should be reviewed first, and this one should be merged as a consequence of a ✔️ on the main PR.

[Aiden2244]

In which way is this blocked?

I updated the main PR linked to read the constants from this JSON spec instead of leaving them in the source code (one of the suggestions was to move the magic numbers outside of the source file). If you think it would be cleaner to merge the main archspec PR first, that is ok with me, but I would have to revert it so that the "magic numbers" are once again in the source code. That's why this is a blocker at the moment.