David Edmundson authored Jun 25, 2020 and David Redondo committed Mar 22, 2021

We might want to present the process list in several different views.
The process list is quite expensive, so if we ref-count the core we can
use it in multiple places.

Timers remain in their respecitive views as Processes has it's own
internal throttling mechanism.

Because that leaves us with a ref-counting issue on which plugin
attributes are enabled or not, that is changed to be implicit based on
whether we have dataChanged connected or not; which actually simplifies
some code.

Co-authored-by: David Redondo <kde@david-redondo.de>