Improve CPU table/display

[ClementTsang]

Describe the feature request

Why should we consider this feature request? Describe why, and/or how you think this feature will solve the issue, or overall improve the application:

As mentioned in https://github.com/ClementTsang/bottom/issues/132, it's hard to use the CPU chart with many cores.

Seems like it's worth doing a bit of an overhaul with the CPU display. Admittedly, the current design is a bit of an afterthought.

Ideas:

• [ ] ~~Bring in --basic's bar to give a better indication of usage within the legend section. Option to disable is needed. Test if it looks good at all. Maybe will do, maybe won't.~~ Not really a fan of how it might look

• [x] ~~Redo the whole "hiding cores" thing. It's a bit dumb and unintuitive. Not sure what to make it into though, but something to show specific cores easily, and hide others is something I could see being useful.~~

  Removed the entire "hiding cores" thing, use below as a solution. May come up with something better.

• [x] Currently thinking of making scrolling through an entry only show that entry, so it's obvious what line is what core and be clear.

• [ ] Searching by core, perhaps? Or some way of instantly jumping to a core - something like vim line jumping (don't we love just using vim commands)?

• [ ] Adding a "multi-graph" solution - inspired by, of all things, Windows task manager. This would hopefully be an easier way to see multiple core performance at once.

• [ ] Considering a simple multi-core visualization as well to quickly show usage. Again, idea "inspired" by Windows task manager

Additional context/details

Provide any additional context or details here. What needs to be done, why, etc:

[mfarrugi]

For what it's worth, seeing the total cpu usage and/or the Use% of each core is more relevant (so worth more space!) than the graph when there are many cores. The graph ends up being noise when not zoomed in.