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/surgery/bodyparts/_bodyparts.dm

@@ -977,7 +977,7 @@
 		bleed_rate += 0.5
 
 	//We want an accurate reading of .len
-	listclearnulls(embedded_objects)
+	list_clear_nulls(embedded_objects)
 	for(var/obj/item/embeddies in embedded_objects)
 		if(!embeddies.isEmbedHarmless())
 			bleed_rate += 0.25

code/modules/surgery/organ_manipulation.dm

@@ -118,7 +118,7 @@
 				organs -= organ
 				organs[organ.name] = organ
 
-			target_organ = input("Remove which organ?", "Surgery", null, null) as null|anything in sortList(organs)
+			target_organ = input("Remove which organ?", "Surgery", null, null) as null|anything in sort_list(organs)
 			if(target_organ && user && target && user.Adjacent(target) && user.get_active_held_item() == tool)
 				target_organ = organs[target_organ]
 				if(!target_organ)