Add local APC cache to /area (#61655)

About The Pull Request

for(var/obj/machinery/power/apc/APC in GLOB.apcs_list) in get_apc makes chuck norris shed a tear
Why It's Good For The Game

tears are bad
Changelog

cl
code: /area now retains a local reference to the APC in the area, if any
/cl

code/modules/modular_computers/file_system/programs/powermonitor.dm

@@ -44,7 +44,7 @@
 	var/area/A = get_area(computer) //if the computer isn't directly connected to a wire, attempt to find the APC powering it to pull it's powernet instead
 	if(!A)
 		return
-	local_apc = A.get_apc()
+	local_apc = A.apc
 	if(!local_apc)
 		return
 	if(!local_apc.terminal) //this really shouldn't happen without badminnery.