Makes the preloader apply text macros: Re-engineering (#24614)

* Add apply_text_macros

* Make the map loader use text macros

* Cleanup

code/modules/mapping/reader.dm

@@ -436,6 +436,8 @@ var/global/dmm_suite/preloader/_preloader = new
 		var/value = attributes[attribute]
 		if(islist(value))
 			value = deepCopyList(value)
+		if(istext(value))
+			value = apply_text_macros(value)
 		what.vars[attribute] = value
 	use_preloader = FALSE