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/effects/burnt_wall.dm

@@ -3,15 +3,15 @@
 	desc = "A wall that had a hole burnt into it. Nasty."
 	icon = 'icons/turf/flooring/plating.dmi'
 	icon_state = "wall_thermite"
-	var/material/material
-	var/material/reinf_material
+	var/singleton/material/material
+	var/singleton/material/reinf_material
 
 /obj/effect/overlay/burnt_wall/Initialize(mapload, new_name, new_mat, new_reinf_mat)
 	. = ..()
 	name = "burnt [new_name]"
-	material = SSmaterials.get_material_by_name(new_mat)
+	material = GET_SINGLETON(new_mat)
 	if(new_reinf_mat)
-		reinf_material = SSmaterials.get_material_by_name(new_reinf_mat)
+		reinf_material = GET_SINGLETON(new_reinf_mat)
 	color = material.icon_colour
 	if(material.opacity < 0.5)
 		alpha = 125

code/game/objects/effects/chem/foam.dm

@@ -208,7 +208,7 @@
 			to_chat(user, SPAN_NOTICE("There isn't enough material here to construct a wall."))
 			return TRUE
 
-		var/material/M = SSmaterials.get_material_by_name(S.default_type)
+		var/singleton/material/M = GET_SINGLETON(S.default_type)
 		if(!istype(M))
 			return TRUE
 		if(M.integrity < 50)