Remove a whole bunch of in world loops and rework machinery global lists (#3053)

Removes a whole bunch of in world loops.
Reworks SSmachinery to hold two lists: all_machines and processing_machines. all_machines contains all machines 5ever. All of them. Literally. Forever. And ever. processing_machines only contains machines that process with the SSmachinery controller.

I checked most types at runtime on the live server to see whether they're in processing_machines or in all_machines, and did debug to ensure that most machinery ends up and stays in all_machines.

Includes a basic UT to make sure all mapped in machinery types remain within the all_machines list post-init.

code/modules/power/singularity/field_generator.dm

@@ -312,7 +312,7 @@ field_generator power level display
 	//I want to avoid using global variables.
 	spawn(1)
 		var/temp = 1 //stops spam
-		for(var/obj/singularity/O in machines)
+		for(var/obj/singularity/O in SSmachinery.processing_machines)
 			if(O.last_warning && temp)
 				if((world.time - O.last_warning) > 50) //to stop message-spam
 					temp = 0

code/modules/power/singularity/singularity.dm

@@ -39,7 +39,7 @@
 
 	..()
 	START_PROCESSING(SScalamity, src)
-	for(var/obj/machinery/power/singularity_beacon/singubeacon in machines)
+	for(var/obj/machinery/power/singularity_beacon/singubeacon in SSmachinery.processing_machines)
 		if(singubeacon.active)
 			target = singubeacon
 			break
@@ -516,4 +516,4 @@
 /obj/singularity/proc/zMove(direction)
 	var/turf/destination = (direction == UP) ? GetAbove(src) : GetBelow(src)
 	if(destination)
-		forceMove(destination)
+		forceMove(destination)