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/game/objects/structures/machinery/deployable.dm

@@ -31,7 +31,7 @@ Deployable Kits
 /obj/structure/blocker/proc/set_material(var/material_name)
 	if(force_material)
 		material_name = force_material
-	material = SSmaterials.get_material_by_name(material_name)
+	material = GET_SINGLETON(material_name)
 	if(!material)
 		qdel(src)
 		return