[Feature Request] Option to create CPU groups and show per-group averages

[Burnus]

Checklist

• I've looked through the documentation and existing open issues for similar feature requests.

Describe the feature request

Some computers nowadays have different types of CPU for different purposes. For instance, current Macs ship with high efficiency cores as well as high performance cores. These are treated differently by the system, so I would prefer to be able to see the average utilisation per group rather than the average over all of them combined.