cleanup _HELPERS/_lists.dm and all the necessary files (#61827)

Bring _HELPERS/_lists.dm to latest standards by:
-Adding proper documentation and fixing existing one
-Giving vars proper names
-Procs now use snake case as per standard (many files that use those procs will be affected)

code/modules/mapping/preloader.dm

@@ -20,7 +20,7 @@ GLOBAL_DATUM_INIT(_preloader, /datum/map_preloader, new)
 	for(var/attribute in preloader_local.attributes)
 		var/value = preloader_local.attributes[attribute]
 		if(islist(value))
-			value = deepCopyList(value)
+			value = deep_copy_list(value)
 		#ifdef TESTING
 		if(what.vars[attribute] == value)
 			var/message = "<font color=green>[what.type]</font> at [AREACOORD(what)] - <b>VAR:</b> <font color=red>[attribute] = [isnull(value) ? "null" : (isnum(value) ? value : "\"[value]\"")]</font>"

code/modules/mapping/ruins.dm

@@ -101,7 +101,7 @@
 				forced = TRUE
 				break
 		else //Otherwise just pick random one
-			current_pick = pickweight(ruins_available)
+			current_pick = pick_weight(ruins_available)
 
 		var/placement_tries = forced_turf ? 1 : PLACEMENT_TRIES //Only try once if we target specific turf
 		var/failed_to_place = TRUE