Mothic Fleet Rations now leave trash (tgstation#81280)

## About The Pull Request

During the feature freeze someone pointed out that it was weird that
mothic rations can get dirty if dropped on the floor, as they're
supposed to be inside wrappers.
I added a trash type to them, which has the added side-effect of the
game assuming that if it leaves trash it probably doesn't get dirty when
dropped on the ground.

I also changed the colour of the text on the wrapper from black to very
very dark brown because I didn't like drawing it in black on the
wrapper.

## Why It's Good For The Game

More immersive. More Janitor content.

## Changelog

:cl:
add: Mothic Fleet Rations now no longer get dirty or decompose if left
on the floor, due to their wrappers.
/:cl:

code/game/objects/items/food/moth.dm

@@ -419,6 +419,7 @@
 		they do eventually go bad- prompting them to be sold as surplus by the fleet. This particular one is, like most artificially-flavoured moth food, mixed-herb flavoured."
 	icon = 'icons/obj/food/moth.dmi'
 	icon_state = "sustenance_bar"
+	trash_type = /obj/item/trash/fleet_ration
 	food_reagents = list(/datum/reagent/consumable/nutriment = 20)
 	tastes = list("herbs" = 1)
 	foodtypes = VEGETABLES | GRAIN

code/game/objects/items/trash.dm

@@ -80,6 +80,11 @@
 	name = "energybar wrapper"
 	icon_state = "energybar"
 
+/obj/item/trash/fleet_ration
+	name = "surplus fleet wrapper"
+	desc = "In the Mothic Fleet every individual wrapper is carefully recycled and repurposed into fresh material. Over here they are more commonly dropped directly onto the floor."
+	icon_state = "moth_ration"
+
 /obj/item/trash/waffles
 	name = "waffles tray"
 	icon_state = "waffles"