Track subsystem runtimes via usr

[Absolucy]

About The Pull Request

Port of my own upstream PR, tgstation/tgstation#87448

This adds a dummy "subsystem tracker" mob to every subsystem - which is set to usr during SS preinit, init and fire. (surely this can't go wrong at all)

If usr is a subsystem tracker during a runtime, it'll replace usr: blahblahblah in the runtime text with subsystem: SSwhatever (/datum/controller/subsystem/whatever)

Also, this makes a /mob/abstract type, and repaths /mob/oranges_ear to /mob/abstract/oranges_ear, so that it can share the "technically this is mob but it's not really a mob" behavior with the dummy tracker mob.

Also, I made it add the subsystem type to the structured logging data for runtimes.

blame MSO.

Why It's Good For The Game

makes runtimes slightly easier to read

Changelog

not user-facing.

[Absolucy]

catgirl accidentally causes worst warops round ever, asked to never do this again