USCM Chestrig (cmss13-devs#5620)

# About the pull request

Adds a resprite of the USCM Welder-Chestrig in the form of the USCM
chestrig. An alternative to a standard satchel, same carry capacity.

# Explain why it's good for the game

Alternative ways for players to customize their apperance, I also feel a
chestrig feels more thematic/in universe than a satchel. In terms of
balance, this has no change since the chestrig has the same inventory
size as a normal satchel.


# Testing Photographs and Procedure
<details>
<summary>Screenshots & Videos</summary>

![Screenshot 2024-02-01 14 37
08](https://github.com/cmss13-devs/cmss13/assets/6595389/03e2cf8e-acc8-4d89-b97f-b7fdae5232bd)

Top: Armour, No Chestrig
Middle: Armour, Wearing Chestrig
Bottom: No Clothing, Wearing Chestrig


![68747470733a2f2f696462322e616666656374656461726330372e636f2e756b2f696d616765732f32363339313036312f353632302f31383138333932393938363438303035393532372e706e67](https://github.com/cmss13-devs/cmss13/assets/6595389/a5ea0ef7-abb8-4d77-bed1-a35d5da14426)

![68747470733a2f2f696462322e616666656374656461726330372e636f2e756b2f696d616765732f32363339313036312f353632302f363538303434393939383737383935313333352e706e67](https://github.com/cmss13-devs/cmss13/assets/6595389/de64065f-d739-412a-8ce5-9c03e91a8130)


</details>


# Changelog
:cl:
add: USCM Chestrig has been added to squad prep vendors, alternative
sprite of a satchel, similar in appearance to the welder-chestrig.
/:cl:

Co-authored-by: Steelpoint <[email protected]>

code/game/machinery/vending/vendor_types/squad_prep/squad_prep.dm

@@ -130,6 +130,7 @@
 		list("Technician Backpack", round(scale * 15), /obj/item/storage/backpack/marine/tech, VENDOR_ITEM_REGULAR),
 		list("Medical Backpack", round(scale * 15), /obj/item/storage/backpack/marine/medic, VENDOR_ITEM_REGULAR),
 		list("USCM Satchel", round(scale * 15), /obj/item/storage/backpack/marine/satchel, VENDOR_ITEM_REGULAR),
+		list("USCM Chestrig", round(scale * 15), /obj/item/storage/backpack/marine/satchel/chestrig, VENDOR_ITEM_REGULAR),
 		list("USCM Technical Satchel", round(scale * 15), /obj/item/storage/backpack/marine/satchel/tech, VENDOR_ITEM_REGULAR),
 		list("USCM Technical Chestrig", round(scale * 15), /obj/item/storage/backpack/marine/engineerpack/welder_chestrig, VENDOR_ITEM_REGULAR),
 		list("Medical Satchel", round(scale * 15), /obj/item/storage/backpack/marine/satchel/medic, VENDOR_ITEM_REGULAR),

code/game/objects/items/storage/backpack.dm

@@ -494,6 +494,11 @@
 	desc = "A heavy-duty chestrig used by some USCM technicians."
 	icon_state = "marinesatch_techi"
 
+/obj/item/storage/backpack/marine/satchel/chestrig
+	name = "\improper USCM chestrig"
+	desc = "A chestrig used by some USCM personnel."
+	icon_state = "chestrig"
+
 GLOBAL_LIST_EMPTY_TYPED(radio_packs, /obj/item/storage/backpack/marine/satchel/rto)
 
 /obj/item/storage/backpack/marine/satchel/rto