Update SSOverlays (ported from Baystation) (#19051)

Our SSOverlays system is outdated, and is likely the cause of many of
the issues seen in #18895. It has also been linked to a massive server
performance decrease.

This brings an updated system from Baystation, hopefully with speed
increases.

Should be testmerged, ideally with #18895.

---------

Co-authored-by: Cody Brittain <cbrittain10@live.com>

code/game/objects/structures/vr/_remote_chair.dm

@@ -47,7 +47,7 @@
 		if(H.old_mob)
 			to_chat(H, SPAN_WARNING("The chair rejects you! You cannot recursively control bodies."))
 			return
-	add_overlay(image('icons/obj/furniture.dmi', src, "vr_helmet", FLY_LAYER))
+	AddOverlays(image('icons/obj/furniture.dmi', src, "vr_helmet", FLY_LAYER))
 	START_PROCESSING(SSprocessing, src)
 
 
@@ -64,6 +64,6 @@
 		var/mob/M = buckled
 		if(istype(M) && M.vr_mob)
 			M.vr_mob.body_return()
-		cut_overlays()
+		ClearOverlays()
 		STOP_PROCESSING(SSprocessing, src)
 	..()