Unhardcodes mech ammo empty sprites (#70056)

* Does some code for improving mecha ammo sprites, de-hardcoding it for downstreams, and adds a var to delete itself when empty instead.

code/modules/vehicles/mecha/equipment/weapons/mecha_ammo.dm

@@ -10,6 +10,8 @@
 	var/direct_load //For weapons where we re-load the weapon itself rather than adding to the ammo storage.
 	var/load_audio = 'sound/weapons/gun/general/mag_bullet_insert.ogg'
 	var/ammo_type
+	/// whether to qdel this mecha_ammo when it becomes empty
+	var/qdel_on_empty = FALSE
 
 /obj/item/mecha_ammo/update_name()
 	. = ..()
@@ -20,7 +22,7 @@
 	desc = rounds ? initial(desc) : "An exosuit ammuniton box that has since been emptied. It can be safely folded for recycling."
 
 /obj/item/mecha_ammo/update_icon_state()
-	icon_state = rounds ? initial(icon_state) : "empty"
+	icon_state = rounds ? initial(icon_state) : "[initial(icon_state)]_e"
 	return ..()
 
 /obj/item/mecha_ammo/attack_self(mob/user)

code/modules/vehicles/mecha/mecha_defense.dm

@@ -418,6 +418,9 @@
 			gun.projectiles_cache = gun.projectiles_cache + A.rounds
 		playsound(get_turf(user),A.load_audio,50,TRUE)
 		to_chat(user, span_notice("You add [A.rounds] [A.ammo_type][A.rounds > 1?"s":""] to the [gun.name]"))
+		if(A.qdel_on_empty)
+			qdel(A)
+			return TRUE
 		A.rounds = 0
 		A.set_custom_materials(list(/datum/material/iron=2000))
 		A.update_appearance()