Unit test material checks are now performed on all crafting recipes by default. All stack recipes now transfer mats to the results (#92620)

## About The Pull Request
Extends the part of the crafting unit test that ensures consistency
between the total mats of the components of a recipe (or rather, the
result of said recipe) and a generic instance of the same type as its
result, previously only implemented on food recipes.

## Why It's Good For The Game
This ensures a degree of consistency with the material composition of
various objects in the game. I couldn't do it in the original PR as that
one was too big already and it took months to get it merged, and have
the relative bugs fixed.

Currently a WIP as I slowly deal with the unit test reports.

## Changelog

🆑
refactor: Follow-up to the crafting/material refactor from months ago.
All objects crafted with stacks now inherit their mat composition (not
necessarily the effects and color) by default, while previously only a
few things like chair, sinks and toilets did. Report any object looking
or behaving weirdly as a result.
fix: The material composition of ammo boxes is no longer a 1/10 of what
it's supposed to be. It was a shitty hack to make it harder to recycle
empty ammo boxes. Instead, they lose materials as they're emptied now.
/🆑

code/modules/instruments/items.dm

@@ -48,6 +48,7 @@
 	inhand_icon_state = "violin"
 	hitsound = SFX_SWING_HIT
 	allowed_instrument_ids = "violin"
+	custom_materials = list(/datum/material/wood = SHEET_MATERIAL_AMOUNT * 4, /datum/material/iron = SHEET_MATERIAL_AMOUNT)
 
 /obj/item/instrument/violin/golden
 	name = "golden violin"
@@ -55,6 +56,7 @@
 	icon_state = "golden_violin"
 	inhand_icon_state = "golden_violin"
 	resistance_flags = LAVA_PROOF | FIRE_PROOF | ACID_PROOF
+	custom_materials = list(/datum/material/gold = SHEET_MATERIAL_AMOUNT * 4, /datum/material/iron = SHEET_MATERIAL_AMOUNT)
 
 /obj/item/instrument/banjo
 	name = "banjo"