[Feature] Add processes stat like htop

[kchennen]

Checklist

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

Describe the feature request

It would be great to have processes stats like in htop. Ex: - number of tasks, threads, running, Load average...

[ClementTsang]

• Kinda a duplicate of Thread support and highlighting #228 in regards to threads, will look at at some point.

• Things like "running" are covered already by state, if that's what you mean.

• For load average, do you mean CPU load average? As that's reported in the CPU widget atm
  

  Though I can see being able to move that around/have it as a separate widget would be a nice feature.

[ClementTsang]

As for number of processes, technically that's kinda covered if you enable show_table_scroll_position but that's admittedly not a great answer. It might be interesting to put that in some separate "processes summary" widget, I guess.