Cargo elevator overhaul (#21430)

## About PR

Implements an animation logic heavily inspired from CM-SS13 elevators.
Elevator hatch and shaft sprites are courtesy of @KingOfThePing!

Currently if something is standing on the hatches when the elevator is
arriving, they'll be sent to CC level, fall, get paralyzed and severely
injured enough to have broken bones/arterial bleeding.

This PR also fixes cargo announcement screens not displaying elevator
ETA.

## Images

<details><summary>Elevator arriving</summary>
<p>



https://github.com/user-attachments/assets/34879994-d10b-4cb6-959e-314ec20411b8

</p>
</details> 

<details><summary>Elevator departing</summary>
<p>


https://github.com/user-attachments/assets/c345fd3b-07eb-4922-9b28-31cf40842da1

</p>
</details> 

<details><summary>Unfortunate victims falling to the pit</summary>
<p>



https://github.com/user-attachments/assets/98feac04-5d65-4383-8abc-363ce51a028a


</p>
</details> 

### Asset Licenses
The following assets that **have not** been created by myself are
included in this PR:

| Path | Original Author | License |
| --- | --- | --- |
| icons/effect/224x192.dmi | KingOfThePing | CC BY-SA 3.0 |
| icons/obj/doors/retractable_railing.dmi | CM-SS13 | CC BY-SA 3.0 |
| sound/machines/industrial_lift_raising.ogg | CM-SS13 | CC BY-SA 3.0 |
| sound/machines/industrial_lift_lowering.ogg | CM-SS13 | CC BY-SA 3.0 |
| sound/machines/warning-buzzer-2.ogg | Unknown -
https://pixabay.com/sound-effects/incorrect-buzzer-sound-147336/ |
Pixabay Licence |

code/modules/multiz/structures.dm

@@ -351,6 +351,7 @@
 	icon_state = "stairs_railing"
 	anchored = TRUE
 	density = TRUE
+	layer = ABOVE_ABOVE_HUMAN_LAYER
 
 /obj/structure/stairs_railing/CanPass(atom/movable/mover, turf/target, height=0, air_group=0)
 	if(mover?.movement_type & PHASING)