Support stations with multiple z-levels (#35339)

* Remove ZLEVEL_STATION_PRIMARY

* Add Up and Down traits for use by ladders and chasms

* Give map_config creation its own proc

* Combine LoadConfig and ValidateJSON and remove transition_config

* Make space linkage a z-level trait

* Remove ZLEVEL_EMPTY_SPACE

* Update uses of GetFullMapPath

* Handle multi-Z stations and load Lavaland and Reebe at runtime

* Remove unused space maps

* Fix inappropriate z-expansion in map reader, improve logging

* Update comments relating to z-level configuration

* Add Lavaland and Reebe to ALL_MAPS

code/modules/mapping/space_management/space_transition.dm

@@ -1,9 +1,8 @@
 /datum/space_level/proc/set_linkage(new_linkage)
 	linkage = new_linkage
 	if(linkage == SELFLOOPING)
-		neigbours = list()
-		var/list/L = list(TEXT_NORTH,TEXT_SOUTH,TEXT_EAST,TEXT_WEST)
-		for(var/A in L)
+		neigbours = list(TEXT_NORTH,TEXT_SOUTH,TEXT_EAST,TEXT_WEST)
+		for(var/A in neigbours)
 			neigbours[A] = src
 
 /datum/space_level/proc/set_neigbours(list/L)