Adds Neon Carpet (#55782)

* Adds emissive carpet, adds plane support to decal element

- Adds a basic abstract/debugging emissive carpet
- Makes decals capable of supporting plane
- Adds auto-smoothing decals

* Adds simple neon carpet variations

* Adds neon carpet reagents and recipes

* Refactors emissive blockers to allow multiple layers of emissive / emissive blocking objects

- Splits the emissive and emissive blocker plane masters into several plane masters which handle different layers of emissiveness.

* Makes neon carpet tile stacks emissive

* Rearranges and docs some emissive plane masters

- Folds the overlay lighting plane master into the emissive planes since it is also used to mask the lighting plane

* Fixes null mats_per_unit stack recombining after splitting

- I think I broke this a while ago when I reworked how stacks handle materials. Whoops.
- This basically only effects carpet at the moment. Good thing I did this when I did!

* Adds neon carpets to cargo

- Adds a cargo supply crate containing a _lot_ of neon carpets for 3000 credits

* Fixes neon carpet highlights leaking through vending machines and such

- Turns out vending machines axed their own emissive blockers whenever they updated their icon because they cleared their managed_vis_overlays...
- Generic emissive blocking has been elementized and some update_overlays procs have been straightened out.

* Fixes id_arg_index for the emissive blocker element

* Commits @Rohsie's suggestions

code/modules/lighting/emissive_blocker.dm

@@ -9,7 +9,7 @@
 /atom/movable/emissive_blocker
 	name = ""
 	plane = EMISSIVE_BLOCKER_PLANE
-	layer = EMISSIVE_BLOCKER_LAYER
+	layer = EMISSIVE_LAYER
 	mouse_opacity = MOUSE_OPACITY_TRANSPARENT
 	//Why?
 	//render_targets copy the transform of the target as well, but vis_contents also applies the transform
@@ -17,11 +17,12 @@
 	//Since only render_target handles transform we don't get any applied transform "stacking"
 	appearance_flags = RESET_TRANSFORM
 
-/atom/movable/emissive_blocker/Initialize(mapload, source)
+/atom/movable/emissive_blocker/Initialize(mapload, source, render_plane = EMISSIVE_BLOCKER_PLANE)
 	. = ..()
 	verbs.Cut() //Cargo culting from lighting object, this maybe affects memory usage?
 
 	render_source = source
+	plane = render_plane
 
 /atom/movable/emissive_blocker/ex_act(severity)
 	return FALSE