Add Railings "Caps" for Aesthetic Use. (#21803)

* Add railing caps
-subtype of railing corners

* Batch of changes:
- Fixed cap sprite
- Added 2 more instances of caps (left and right)
- Added caps to rods crafting menu
- Changed cost of corner from 3 to 2
- Added cost to cap, it cost 2 rods

* Woops:
- Apparently railings corners and such borrow code from normal railing so they always drop 3 rods.

* Change railings to list

* removed density/climbable
- they inhert it from railing

code/game/objects/structures/railings.dm

@@ -17,6 +17,17 @@
 	density = FALSE
 	climbable = FALSE
 
+/obj/structure/railing/cap //aestetic "end" for railing
+	icon_state = "railing_cap"
+	density = FALSE
+	climbable = FALSE
+
+/obj/structure/railing/cap/normal
+	icon_state = "railing_cap_normal"
+
+/obj/structure/railing/cap/reversed
+	icon_state = "railing_cap_reversed"
+
 /obj/structure/railing/attackby(obj/item/I, mob/living/user, params)
 	..()
 	add_fingerprint(user)
@@ -74,6 +85,15 @@
 /obj/structure/railing/corner/CheckExit()
 	return TRUE
 
+/obj/structure/railing/cap/CanPass()
+	return TRUE
+
+/obj/structure/railing/cap/CanPathfindPass(obj/item/card/id/ID, to_dir, caller, no_id = FALSE)
+	return TRUE
+
+/obj/structure/railing/cap/CheckExit()
+	return TRUE
+
 /obj/structure/railing/CanPass(atom/movable/mover, turf/target)
 	if(istype(mover) && mover.checkpass(PASSFENCE))
 		return TRUE