Materials Repath (#22388)

Soft-ish port of https://github.com/NebulaSS13/Nebula/pull/540. Except
we call them singletons.

Repaths all materials as singletons instead of datums, and replaces
material defines from strings to paths so that we can just run
GET_SINGLETON instead of needing to use SSMaterials. This is Step One.

This PR has no player-facing changes.

changes:
  - refactor: "Repaths /material to /singleton/material."
- refactor: "Replaces all material string defines to path defines,
replacing SSmaterials procs w/ GET_SINGLETON instead."
- refactor: "Removes all material var edited objects from all maps,
adding new presets where necessary."
- refactor: "Updates recipes unit test to run all recipes against all
material singletons."

---------

Signed-off-by: Batrachophreno <Batrochophreno@gmail.com>
Co-authored-by: kano-dot <bhutanlikanoxy@gmail.com>

code/modules/integrated_electronics/core/printer.dm

@@ -19,7 +19,7 @@
 /obj/item/integrated_circuit_printer/attackby(obj/item/attacking_item, mob/user)
 	if(istype(attacking_item,/obj/item/stack/material))
 		var/obj/item/stack/material/stack = attacking_item
-		if(stack.material.name == DEFAULT_WALL_MATERIAL)
+		if(stack.material.type == MATERIAL_STEEL)
 			var/num = min((max_metal - metal) / metal_per_sheet, stack.amount)
 			if(num < 1)
 				to_chat(user, SPAN_WARNING("\The [src] is too full to add more metal."))