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.dm

@@ -14,17 +14,16 @@
 	/// Footstep sounds when stepped on
 	var/list/footstep_sound
 
-	var/material/material
+	var/singleton/material/material
 	/// Used by some structures to determine into how many pieces they should disassemble into or be made with
 	var/build_amt = 2
-
 	/// Amount that pulling mobs have their movement delayed by
 	var/slowdown = 0
 
 /obj/structure/Initialize(mapload)
 	. = ..()
 	if(!isnull(material) && !istype(material))
-		material = SSmaterials.get_material_by_name(material)
+		material = GET_SINGLETON(material)
 	if (!mapload)
 		updateVisibility(src)	// No point checking this before visualnet initializes.
 	if(climbable)
@@ -101,9 +100,9 @@
 				add_damage(maxhealth * 0.25)
 
 /obj/structure/proc/dismantle()
-	var/material/dismantle_material
+	var/singleton/material/dismantle_material
 	if(!get_material())
-		dismantle_material = SSmaterials.get_material_by_name(DEFAULT_WALL_MATERIAL) //if there is no defined material, it will use steel
+		dismantle_material = GET_SINGLETON(MATERIAL_STEEL)
 	else
 		dismantle_material = get_material()
 	if(should_use_health && health <= 0)