Integrate FidryCpuCoreCounter

[theofidry]

See theofidry/cpu-core-counter#11 for the motivations.

The code should be sensibly the same, the notable differences are:

• fixed the deprecated usage of hw.ncpu
• /proc/cpuinfo is check last
• nproc is checked first (before was not checked at all, it's considered to be more accurate and less convoluted than cpuinfo though)

Also note since this was analogue to PHPStan, I did the PR there too: phpstan/phpstan-src#2047

I would also wait on 1.x before merging this if you're happy with it. Technically the current version is fine, I'm just looking for a round of feedback before publishing 1.0.

[TomasVotruba]

The CI needs some fixing

[TomasVotruba]

Thank you 👏

Let's try this out in the wild :)