Adds a few turf istype helpers (#20754)

* a very calming act
when the world is too much, too fast

* i'm tired
but i have to be efficient, infinite

* lick your lips at the sight of me
a fantasy made reality

code/modules/holodeck/area_copy.dm

@@ -76,7 +76,7 @@
 			continue
 
 		if(platingRequired)
-			if(istype(B, /turf/open/space))
+			if(isspaceturf(B))
 				continue
 
 		var/old_dir1 = T.dir

code/modules/holodeck/computer.dm

@@ -143,7 +143,7 @@
 
 /obj/machinery/computer/holodeck/proc/floorcheck()
 	for(var/turf/T in linked)
-		if(!T.intact || istype(T,/turf/open/space))
+		if(!T.intact || isspaceturf(T))
 			return 0
 	return 1