Print an error log when the CPU doesn't have the required features

[jancionear]

We have specific requirements for features that should be supported by CPUs that neard runs on: https://near-nodes.io/validator/hardware
We tried to make these features required to run neard (#11711), but that was met with heavy pushback from the community who wants to run their nodes on unsupported hardware, even if it might turn out to be too slow. The change was eventually rolled back in #11973.

Let's check the CPU features on startup and print an error message if the required features are not there. This will let node operators know that they should upgrade the hardware without crashing the node in a weird way.
/cc @nagisa