Soporific magazines use the correct icon, penetrator and marksman magazines now have icons. (#73217)

## About The Pull Request

Fixes #73192

Soporific sniper rifle magazines had used the wrong icon, I've fixed
this, I'm also re-purposed an old unused magazine sprite and added a new
one for the other 2 sniper ammo types.
## Why It's Good For The Game

Bug fix + now the alt sniper ammo types have unique sprites.
## Changelog
🆑
fix: Soporific sniper magazines use the correct icon again.
imageadd: Penetrator and Marksman sniper magazines now have icons.
/🆑

code/modules/projectiles/boxes_magazines/external/sniper.dm

@@ -13,19 +13,20 @@
 /obj/item/ammo_box/magazine/sniper_rounds/soporific
 	name = "sniper rounds (Zzzzz)"
 	desc = "Soporific sniper rounds, designed for happy days and dead quiet nights..."
-	icon_state = "soporific"
+	base_icon_state = "soporific"
 	ammo_type = /obj/item/ammo_casing/p50/soporific
 	max_ammo = 3
-	caliber = CALIBER_50
 
 /obj/item/ammo_box/magazine/sniper_rounds/penetrator
 	name = "sniper rounds (penetrator)"
 	desc = "An extremely powerful round capable of passing straight through cover and anyone unfortunate enough to be behind it."
+	base_icon_state = "penetrator"
 	ammo_type = /obj/item/ammo_casing/p50/penetrator
 	max_ammo = 5
 
 /obj/item/ammo_box/magazine/sniper_rounds/marksman
 	name = "sniper rounds (marksman)"
 	desc = "An extremely fast sniper round able to pretty much instantly shoot through something."
+	base_icon_state = "marksman"
 	ammo_type = /obj/item/ammo_casing/p50/marksman
 	max_ammo = 5