Add a graphless CPU widget

[ClementTsang]

Checklist

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

Describe the feature request

See https://github.com/ClementTsang/bottom/issues/156#issuecomment-2259827897 and similar.

[qaako]

Thank you for looking into this. I don't know if it's considered spam to give thanks, if so, you can delete this comment.