Replacing objects with their mapping directional helpers Part 1 (#94059)

## About The Pull Request
Improving upon #93662 where i noticed a lot of objects don't have
directional helpers

Replaces the following mapped in objects with their directional
counterpart

- `/obj/structure/sign/nanotrasen ->
/obj/structure/sign/nanotrasen/directional`

less var edits & also more realistic interaction with fire/acid etc if
the turf on which they are placed on is attacked which isn't the case if
they are directly mounted on walls

## Changelog
🆑
qol: adds mapping directional helper for nanotrasen sign & replaces all
var edited instances
/🆑

code/game/objects/structures/signs/_signs.dm

@@ -129,19 +129,6 @@
 	is_editable = TRUE
 	sign_change_name = "Blank Sign"
 
-/obj/structure/sign/nanotrasen
-	name = "\improper Nanotrasen logo sign"
-	sign_change_name = "Corporate Logo - Nanotrasen"
-	desc = "A sign with the Nanotrasen logo on it. Glory to Nanotrasen!"
-	icon_state = "nanotrasen"
-	is_editable = TRUE
-
-/obj/structure/sign/logo
-	name = "\improper Nanotrasen logo sign"
-	desc = "The Nanotrasen corporate logo."
-	icon_state = "nanotrasen_sign1"
-	buildable_sign = FALSE
-
 /obj/item/sign
 	name = "sign backing"
 	desc = "A plastic sign backing, use a pen to change the decal. It can be placed on a wall."

code/game/objects/structures/signs/signs_misc.dm

@@ -109,3 +109,18 @@ MAPPING_DIRECTIONAL_HELPERS(/obj/structure/sign/xenobio_guide, 32)
 	return data
 
 MAPPING_DIRECTIONAL_HELPERS(/obj/structure/sign/tram_plate, 32)
+
+/obj/structure/sign/nanotrasen
+	name = "\improper Nanotrasen logo sign"
+	sign_change_name = "Corporate Logo - Nanotrasen"
+	desc = "A sign with the Nanotrasen logo on it. Glory to Nanotrasen!"
+	icon_state = "nanotrasen"
+	is_editable = TRUE
+
+MAPPING_DIRECTIONAL_HELPERS(/obj/structure/sign/nanotrasen, 32)
+
+/obj/structure/sign/logo
+	name = "\improper Nanotrasen logo sign"
+	desc = "The Nanotrasen corporate logo."
+	icon_state = "nanotrasen_sign1"
+	buildable_sign = FALSE