refactoring how materials effects are added to atoms (#86901)

## About The Pull Request
I'm "cooking" the materials system a bit, specifically the code
responsible for applying and removing effects. My goal is to move most
of the code to the objects-side, split it in smaller procs that can be
more easily overriden or called for object-specific modifiers and
effects, while also revamping things all around to better support items
made from multiple materials (the cleric mace will most likely be one in
this PR, with the handle and tip made of different materials).

PR NO LONGER WIP, TESTED AND ALL, CLERIC MACES CAN NOW BE MADE OF TWO
MATERIALS.

## Why It's Good For The Game
One of the nastiest flaws with the materials system is that it's just
unfeasable to have items made of multiple mats (with effects enabled)
right now, as they easily tend to override each other, where some of the
modifiers and effects should only be applied the main material.

Beside, the system's starting to show signs of its time, from the
several type checks used to apply different effects, the one letter
variables to the the material flags that are still being passed down as
arguments when you can access them from the atom/source arg anyway. It
would be disonhest of me if I went ahead and coded material fishing rods
or whatever fish fuckery with materials without ensuring it won't
further the technical debt the feature currently has.

## Changelog
🆑
refactor: Refactored materials code. report any issue.
add: Cleric maces (The autolathe-printable weapon design from outer
space) can now be made of two different materials.
balance: Buffed cleric maces a little.
fix: toolboxes' stats are now affected by materials again.
/🆑

---------

Co-authored-by: _0Steven <42909981+00-Steven@users.noreply.github.com>

code/game/objects/items/stacks/stack.dm

@@ -77,18 +77,19 @@
 		amount = new_amount
 	while(amount > max_amount)
 		amount -= max_amount
-		new type(loc, max_amount, FALSE)
+		new type(loc, max_amount, FALSE, mat_override, mat_amt)
 	if(!merge_type)
 		merge_type = type
 
-	if(LAZYLEN(mat_override))
-		set_mats_per_unit(mat_override, mat_amt)
-	else if(LAZYLEN(mats_per_unit))
-		set_mats_per_unit(mats_per_unit, 1)
-	else if(LAZYLEN(custom_materials))
-		set_mats_per_unit(custom_materials, amount ? 1/amount : 1)
-
 	. = ..()
+
+	var/materials_mult = amount
+	if(LAZYLEN(mat_override))
+		materials_mult *= mat_amt
+		mats_per_unit = mat_override
+	if(LAZYLEN(mats_per_unit))
+		initialize_materials(mats_per_unit, materials_mult)
+
 	if(merge)
 		for(var/obj/item/stack/item_stack in loc)
 			if(item_stack == src)
@@ -118,26 +119,15 @@
 	if(is_path_in_list(merge_type, GLOB.golem_stack_food_directory))
 		AddComponent(/datum/component/golem_food, golem_food_key = merge_type)
 
-/** Sets the amount of materials per unit for this stack.
- *
- * Arguments:
- * - [mats][/list]: The value to set the mats per unit to.
- * - multiplier: The amount to multiply the mats per unit by. Defaults to 1.
- */
-/obj/item/stack/proc/set_mats_per_unit(list/mats, multiplier=1)
-	mats_per_unit = SSmaterials.FindOrCreateMaterialCombo(mats, multiplier)
-	update_custom_materials()
-
-/** Updates the custom materials list of this stack.
- */
+///Called to lazily update the materials of the item whenever the used or if more is added
 /obj/item/stack/proc/update_custom_materials()
-	set_custom_materials(mats_per_unit, amount, is_update=TRUE)
+	if(length(mats_per_unit))
+		set_custom_materials(mats_per_unit, amount)
 
-/**
- * Override to make things like metalgen accurately set custom materials
- */
-/obj/item/stack/set_custom_materials(list/materials, multiplier=1, is_update=FALSE)
-	return is_update ? ..() : set_mats_per_unit(materials, multiplier/(amount || 1))
+/obj/item/stack/apply_material_effects(list/materials)
+	. = ..()
+	if(amount)
+		mats_per_unit = SSmaterials.FindOrCreateMaterialCombo(materials, 1/amount)
 
 /obj/item/stack/blend_requirements()
 	if(is_cyborg)
@@ -440,7 +430,7 @@
 	if((recipe.crafting_flags & CRAFT_APPLIES_MATS) && LAZYLEN(mats_per_unit))
 		if(isstack(created))
 			var/obj/item/stack/crafted_stack = created
-			crafted_stack.set_mats_per_unit(mats_per_unit, recipe.req_amount / recipe.res_amount)
+			crafted_stack.set_custom_materials(mats_per_unit, (recipe.req_amount / recipe.res_amount) * crafted_stack.amount)
 		else
 			created.set_custom_materials(mats_per_unit, recipe.req_amount / recipe.res_amount)
 
@@ -543,8 +533,7 @@
 	amount -= used
 	if(check && is_zero_amount(delete_if_zero = TRUE))
 		return TRUE
-	if(length(mats_per_unit))
-		update_custom_materials()
+	update_custom_materials()
 	update_appearance()
 	update_weight()
 	return TRUE
@@ -591,8 +580,7 @@
 		source.add_charge(_amount * cost)
 	else
 		amount += _amount
-	if(length(mats_per_unit))
-		update_custom_materials()
+	update_custom_materials()
 	update_appearance()
 	update_weight()