Tram signal process/destination improvements (#74072)

## About The Pull Request

- Tram crossing signals now call process() much less often
- Tram crossing signals don't turn amber/red needlessly
- Tram destination landmarks are more generic to accommodate future
maps, like Birdshot
- Renames to_where and from_where, because those vars didn't always
match tram position to/from

## Why It's Good For The Game

Tram works better, uses less processing

## Changelog

🆑 LT3
code: Tram crossing signal/platform logic improvements
/🆑

code/modules/mapfluff/ruins/spaceruin_code/hilbertshotel.dm

@@ -500,19 +500,22 @@ GLOBAL_VAR_INIT(hhMysteryRoomNumber, rand(1, 999999))
 /obj/effect/landmark/lift_id/hilbert
 	specific_lift_id = HILBERT_TRAM
 
-/obj/effect/landmark/tram/left_part/hilbert
+/obj/effect/landmark/tram/hilbert/left
+	name = "Port"
 	specific_lift_id = HILBERT_TRAM
-	destination_id = "left_part_hilbert"
+	platform_code = HILBERT_PORT
 	tgui_icons = list("Reception" = "briefcase", "Botany" = "leaf", "Chemistry" = "flask")
 
-/obj/effect/landmark/tram/middle_part/hilbert
+/obj/effect/landmark/tram/hilbert/middle
+	name = "Central"
 	specific_lift_id = HILBERT_TRAM
-	destination_id = "middle_part_hilbert"
+	platform_code = HILBERT_CENTRAL
 	tgui_icons = list("Processing" = "cogs", "Xenobiology" = "paw")
 
-/obj/effect/landmark/tram/right_part/hilbert
+/obj/effect/landmark/tram/hilbert/right
+	name = "Starboard"
 	specific_lift_id = HILBERT_TRAM
-	destination_id = "right_part_hilbert"
+	platform_code = HILBERT_STARBOARD
 	tgui_icons = list("Ordnance" = "bullseye", "Office" = "user", "Dormitories" = "bed")
 
 /obj/item/keycard/hilbert