generic parent type for both sabre sheaths (#92300)

## About The Pull Request
puts both the grass and normal sabre sheath types under a shared parent
type for shared behavior.
considered subtyping the storage datum but it seemed overkill. can do if
requested.
## Why It's Good For The Game
less copy paste. good if someone wants to add a clay-more sheath for
similar (believe that exists somewhere downstream), would have done it
myself but no sprites.
## Changelog
N/A

code/datums/components/crafting/tailoring.dm

@@ -119,7 +119,7 @@
 
 /datum/crafting_recipe/grass_sheath
 	name = "Grass Sabre Sheath"
-	result = /obj/item/storage/belt/grass_sabre
+	result = /obj/item/storage/belt/sheath/grass_sabre
 	reqs = list(/obj/item/food/grown/grass = 4,
 				/obj/item/food/grown/grass/fairy = 2)
 	time = 4 SECONDS