Enhances algorithm for finding an atom mount (#94076)

## About The Pull Request
Depends on #94064 for the unit test but offers a better method for
finding an atom to mount on
- Finding a mount now takes into consideration the objects pixel x & y
offsets meaning diagonal mounting is now supported. Gives great
flexibility for mappers
- If you don't want to use pixel offsets but default back to using the
objects direction that behaviour is still preserved. Useful if your
object uses directional icon states(lights & cameras for now) AND don't
use offsets
- If no direction could be specified then as the last resort it defaults
back to the objects local turf for mounting

## Changelog
🆑
fix: all mounted objects on tables, fences, windows & walls should fall
of correctly when the atom it is placed on is destroyed
fix: security telescreen now falls off when their mounted wall is
destroyed
fix: defib wall mount falls off when their mounted wall is destroyed
fix: floor lights are mounted to the ground/catwalk/tram floor they are
sitting on meaning destroying it will destroy the light
fix: wall mounted plaques now fall off when their mounted wall is
destroyed
/🆑

code/modules/power/apc/apc_main.dm

@@ -217,7 +217,7 @@
 		setDir(dir)
 		if(abs(offset_old) != APC_PIXEL_OFFSET)
 			log_mapping("APC: ([src]) at [AREACOORD(src)] with dir ([dir] | [uppertext(dir2text(dir))]) has pixel_[dir & (WEST|EAST) ? "x" : "y"] value [offset_old] - should be [dir & (SOUTH|EAST) ? "-" : ""][APC_PIXEL_OFFSET]. Use the directional/ helpers!")
-		find_and_hang_on_atom()
+		find_and_mount_on_atom()
 	// For apcs created during the round players need to configure them from scratch
 	else
 		opened = APC_COVER_OPENED

code/modules/power/lighting/light.dm

@@ -84,11 +84,6 @@
 	///break if moved, if false also makes it ignore if the wall its on breaks
 	var/break_if_moved = TRUE
 
-/obj/machinery/light/Move()
-	if(status != LIGHT_BROKEN && break_if_moved)
-		break_light_tube(TRUE)
-	return ..()
-
 // create a new lighting fixture
 /obj/machinery/light/Initialize(mapload)
 	. = ..()
@@ -121,9 +116,12 @@
 	AddElement(/datum/element/atmos_sensitive, mapload)
 	AddElement(/datum/element/contextual_screentip_bare_hands, rmb_text = "Remove bulb")
 	if(mapload)
-		find_and_hang_on_atom(mark_for_late_init = TRUE)
+		find_and_mount_on_atom(mark_for_late_init = TRUE)
 
-/obj/machinery/light/find_and_hang_on_atom(mark_for_late_init = FALSE, late_init = FALSE)
+/obj/machinery/light/get_turfs_to_mount_on()
+	return list(get_step(src, dir))
+
+/obj/machinery/light/find_and_mount_on_atom(mark_for_late_init, late_init)
 	if(break_if_moved)
 		return ..()
 
@@ -147,6 +145,11 @@
 	QDEL_NULL(cell)
 	return ..()
 
+/obj/machinery/light/Move()
+	if(status != LIGHT_BROKEN && break_if_moved)
+		break_light_tube(TRUE)
+	return ..()
+
 /obj/machinery/light/Exited(atom/movable/gone, direction)
 	. = ..()
 	if(gone == cell)
@@ -753,8 +756,19 @@
 	nightshift_brightness = 4
 	fire_brightness = 4.5
 
-/obj/machinery/light/floor/find_and_hang_on_atom(mark_for_late_init = FALSE, late_init = FALSE)
-	return //its a floor light not a wall light
+/obj/machinery/light/floor/get_turfs_to_mount_on()
+	return list(get_turf(src))
+
+/obj/machinery/light/floor/is_mountable_turf(turf/target)
+	return !isgroundlessturf(target)
+
+/obj/machinery/light/floor/get_moutable_objects()
+	var/static/list/attachables = list(
+		/obj/structure/thermoplastic,
+		/obj/structure/lattice/catwalk,
+	)
+
+	return attachables
 
 /obj/machinery/light/floor/get_light_offset()
 	return list(0, 0)

code/modules/power/lighting/light_construct.dm

@@ -30,16 +30,19 @@
 
 /obj/structure/light_construct/Initialize(mapload)
 	. = ..()
-	if(mapload && !find_and_hang_on_atom(mark_for_late_init = TRUE))
+	if(mapload && !find_and_mount_on_atom(mark_for_late_init = TRUE))
 		return INITIALIZE_HINT_LATELOAD
 
 /obj/structure/light_construct/LateInitialize()
-	find_and_hang_on_atom(late_init = TRUE)
+	find_and_mount_on_atom(late_init = TRUE)
 
 /obj/structure/light_construct/Destroy()
 	QDEL_NULL(cell)
 	return ..()
 
+/obj/structure/light_construct/get_turfs_to_mount_on()
+	return list(get_step(src, dir))
+
 /obj/structure/light_construct/get_cell()
 	return cell
 
@@ -150,7 +153,7 @@
 					if("floor")
 						new_light = new /obj/machinery/light/floor/empty(loc)
 				new_light.setDir(dir)
-				new_light.find_and_hang_on_atom()
+				new_light.find_and_mount_on_atom()
 				transfer_fingerprints_to(new_light)
 				if(!QDELETED(cell))
 					new_light.cell = cell