Shotgun additions and minor tweaks (#3554)

* 24-round shotgun mag fixes + making it relevant.

Adds the AS-24 Shotgun to the traitor uplink for 100 TCs, also makes automatic shotgun magazines costs the appropriate amount (13,000 metal up from 2200)

* Magazine variety.

Nothing really new here. Beanbag / pellet mags for the admin-only AS-24.

* shotgun 6-shell clips, autolathe and shotgun tweaks.

+6-shell quickloader clips for shotguns, with proper metal costs for slugs, beanbags and buckshot.

+minor tweak to shotguns to allow the quickloaders to work in a non-silly way (load_method = SINGLE_CASING|SPEEDLOADER) since there are literally no other shotgun speedloaders this probably shouldn't be an issue (as it's ever so slightly quicker than loading with a box)

+added sprites for quickloading clips.

* Requested changes.

-6 round shotgun clip sprites
+4 round shotgun clip sprites
-/+ adjusted shotgun clips to 4 rounds

* cherrypicking

* fixes

did a bad

* literally a number

code/datums/autolathe/arms.dm

@@ -159,9 +159,18 @@
 	path =/obj/item/ammo_magazine/m762
 	hidden = 1
 
-/datum/category_item/autolathe/arms/shotgun_magazine
-	name = "24rnd shotgun magazine (12g)"
-	path =/obj/item/ammo_magazine/m12gdrum
+/datum/category_item/autolathe/arms/shotgun_clip_slug
+	name = "4-round 12g shell clip (slug)"
+	path =/obj/item/ammo_magazine/clip/c12g
+
+/datum/category_item/autolathe/arms/shotgun_clip_pellet
+	name = "4-round 12g shell clip (buckshot)"
+	path =/obj/item/ammo_magazine/clip/c12g/pellet
+	hidden = 1
+
+/datum/category_item/autolathe/arms/shotgun_clip_beanbag
+	name = "4-round 12g shell clip (beanbag)"
+	path =/obj/item/ammo_magazine/clip/c12g/beanbag
 	hidden = 1
 
 /*