[MIRROR] Mappers Can Now Stop Railings [MDB IGNORE] (#22659)

* Mappers Can Now Stop Railings (#77009)

## About The Pull Request
I MADE RAILING ENDINGS, before, railings could only have straight lines
and curves, meaning that if you wanted to have a seamless rail line, it
had to loop into itself. Now you can just end them.

Look at how ugly this is, they just turn and stop!

![image](https://github.com/tgstation/tgstation/assets/73589390/7e8c645b-9189-4fcc-b760-67fb45b572de)
Look at that pleasant termination of the line of railing

![image](https://github.com/tgstation/tgstation/assets/73589390/53c88022-6664-47a9-96e4-cc19aa788113)

Amazing!

![image](https://github.com/tgstation/tgstation/assets/73589390/afe9d6cd-e053-4032-90c6-ca4b2653a7e3)

I put a few on the North Star as a tech demo (I also removed a single
errant openspace that wasn't supposed to be there)
## Why It's Good For The Game
This PR does nothing but enhance aesthetics for mappers.
## Changelog
🆑
image: Railing ends now exist.
/🆑

* Mappers Can Now Stop Railings

---------

Co-authored-by: Cheshify <73589390+Cheshify@users.noreply.github.com>

code/game/objects/structures/railings.dm

@@ -28,6 +28,12 @@
 	density = FALSE
 	climbable = FALSE
 
+/obj/structure/railing/corner/end //end of a segment of railing without making a loop
+	icon_state = "railing_end"
+
+/obj/structure/railing/corner/end/flip //same as above but flipped around
+	icon_state = "railing_end_flip"
+
 /obj/structure/railing/Initialize(mapload)
 	. = ..()
 	ini_dir = dir