Replaces lava and chasm's "safeties" and ignoring turf slowdown on catwalks with traits and a new element. (#76376)

## About The Pull Request
This adds a new element for movables that grants turfs they're in
traits, changes lava and the chasm component to check for traits
instead, ditto for turf slowdown. It also implements another trait that
prevents wet floor from slipping people, as well as some other changes
(feel free to opine on them really):
- Tables and conveyor belts now stop turf slowdown, much like catwalks,
as I imagine people walking on them are not really touching the floor.
(I'd include protection against lava too... until they melt, but that'd
mean finding a way to have these objects burn in the first place, and
lava code is still stupid despite a years old refactor I did)
- Tables also stop slippery turfs from slipping (bananas, soaps etc.
still apply). I wish there were a way to make some objects slippery by
coating them in water vapor or splashing water/lube, but that's outside
the scope of this PR.
- Fixed an edge case in which a mob standing on a lava turf would be
left permanently visually on fire if the lava is changed to another kind
of turf.
- Removed unused code from stone tiles.

I'm going to include these traits in that global list for admin-added
traits... tomorrow perhaps. 💤

## Why It's Good For The Game
Replacing some hard-coded mechanics with easier to use traits and an
element, which I also need for the submerge element PR.

## Changelog

🆑
refactor: Replaced hardcoded "safeties" for lava, chasms and ignoring
turf slowdowns on catwalks with traits.
balance: much like catwalks, tables and conveyors also disable turf
slowdowns.
balance: slippery turfs won't slip you when walking on a table.
fix: Fixed an edge case in which a mob standing on a lava turf would be
left visually but permanently on fire if the lava is changed to another
kind of turf.
/🆑

code/modules/mapfluff/ruins/objects_and_mobs/necropolis_gate.dm

@@ -240,10 +240,6 @@ GLOBAL_DATUM(necropolis_gate, /obj/structure/necropolis_gate/legion_gate)
 /obj/structure/necropolis_arch/singularity_pull()
 	return 0
 
-#define STABLE 0 //The tile is stable and won't collapse/sink when crossed.
-#define COLLAPSE_ON_CROSS 1 //The tile is unstable and will temporary become unusable when crossed.
-#define DESTROY_ON_CROSS 2 //The tile is nearly broken and will permanently become unusable when crossed.
-#define UNIQUE_EFFECT 3 //The tile has some sort of unique effect when crossed.
 //stone tiles for boss arenas
 /obj/structure/stone_tile
 	name = "stone tile"
@@ -255,69 +251,19 @@ GLOBAL_DATUM(necropolis_gate, /obj/structure/necropolis_gate/legion_gate)
 	resistance_flags = INDESTRUCTIBLE | LAVA_PROOF | FIRE_PROOF | UNACIDABLE | ACID_PROOF
 	var/tile_key = "pristine_tile"
 	var/tile_random_sprite_max = 24
-	var/fall_on_cross = STABLE //If the tile has some sort of effect when crossed
-	var/fallen = FALSE //If the tile is unusable
-	var/falling = FALSE //If the tile is falling
 
 /obj/structure/stone_tile/Initialize(mapload)
 	. = ..()
 	icon_state = "[tile_key][rand(1, tile_random_sprite_max)]"
-	var/static/list/loc_connections = list(
-		COMSIG_ATOM_ENTERED = PROC_REF(on_entered),
-	)
-	AddElement(/datum/element/connect_loc, loc_connections)
+
+	var/static/list/give_turf_traits
+	if(!give_turf_traits)
+		give_turf_traits = string_list(list(TRAIT_LAVA_STOPPED, TRAIT_CHASM_STOPPED))
+	AddElement(/datum/element/give_turf_traits, give_turf_traits)
 
 /obj/structure/stone_tile/singularity_pull()
 	return
 
-/obj/structure/stone_tile/proc/on_entered(datum/source, atom/movable/AM)
-	SIGNAL_HANDLER
-	if(falling || fallen)
-		return
-	var/turf/T = get_turf(src)
-	if(!islava(T) && !ischasm(T)) //nothing to sink or fall into
-		return
-	var/obj/item/I
-	if(isitem(AM))
-		I = AM
-	var/mob/living/L
-	if(isliving(AM))
-		L = AM
-	switch(fall_on_cross)
-		if(COLLAPSE_ON_CROSS, DESTROY_ON_CROSS)
-			if((I && I.w_class >= WEIGHT_CLASS_BULKY) || (L && !(L.movement_type & FLYING) && L.mob_size >= MOB_SIZE_HUMAN)) //too heavy! too big! aaah!
-				INVOKE_ASYNC(src, PROC_REF(collapse))
-		if(UNIQUE_EFFECT)
-			crossed_effect(AM)
-
-/obj/structure/stone_tile/proc/collapse()
-	falling = TRUE
-	var/break_that_sucker = fall_on_cross == DESTROY_ON_CROSS
-	playsound(src, 'sound/effects/pressureplate.ogg', 50, TRUE)
-	Shake(-1, -1, 25)
-	sleep(0.5 SECONDS)
-	if(break_that_sucker)
-		playsound(src, 'sound/effects/break_stone.ogg', 50, TRUE)
-	else
-		playsound(src, 'sound/mecha/mechmove04.ogg', 50, TRUE)
-	animate(src, alpha = 0, pixel_y = pixel_y - 3, time = 5)
-	fallen = TRUE
-	if(break_that_sucker)
-		QDEL_IN(src, 10)
-	else
-		addtimer(CALLBACK(src, PROC_REF(rebuild)), 55)
-
-/obj/structure/stone_tile/proc/rebuild()
-	pixel_x = initial(pixel_x)
-	pixel_y = initial(pixel_y) - 5
-	animate(src, alpha = initial(alpha), pixel_x = initial(pixel_x), pixel_y = initial(pixel_y), time = 30)
-	sleep(3 SECONDS)
-	falling = FALSE
-	fallen = FALSE
-
-/obj/structure/stone_tile/proc/crossed_effect(atom/movable/AM)
-	return
-
 /obj/structure/stone_tile/block
 	name = "stone block"
 	icon_state = "pristine_block1"
@@ -411,8 +357,3 @@ GLOBAL_DATUM(necropolis_gate, /obj/structure/necropolis_gate/legion_gate)
 	name = "burnt stone surrounding tile"
 	icon_state = "burnt_surrounding_tile1"
 	tile_key = "burnt_surrounding_tile"
-
-#undef STABLE
-#undef COLLAPSE_ON_CROSS
-#undef DESTROY_ON_CROSS
-#undef UNIQUE_EFFECT