Makes turfs persist their signals, uses this to optimize connect_loc (#59608)

* Makes turfs persist signals

* Splits connect_loc up into two elements, one for stuff that wishes to connect on behalf of something, and one for stuff that just wants to connect normally. Connecting on behalf of someone has a significant amount of overhead, so let's do this to keep things clear

* Converts all uses of connect_loc over to the new patterns

* Adds some comments, actually makes turfs persist signals

* There's no need to detach connect loc anymore, since all it does is unregister signals. Unregisters a signal from formorly decal'd turfs, and makes the changeturf signal persistance stuff actually work

* bro fuck documentation

* Changes from a var to a proc, prevents admemems and idiots

* Extra detail on why we do the copy post qdel

code/datums/datum.dm

@@ -117,6 +117,14 @@
 			qdel(C, FALSE, TRUE)
 		dc.Cut()
 
+	clear_signal_refs()
+	//END: ECS SHIT
+
+	return QDEL_HINT_QUEUE
+
+///Only override this if you know what you're doing. You do not know what you're doing
+///This is a threat
+/datum/proc/clear_signal_refs()
 	var/list/lookup = comp_lookup
 	if(lookup)
 		for(var/sig in lookup)
@@ -132,9 +140,6 @@
 
 	for(var/target in signal_procs)
 		UnregisterSignal(target, signal_procs[target])
-	//END: ECS SHIT
-
-	return QDEL_HINT_QUEUE
 
 #ifdef DATUMVAR_DEBUGGING_MODE
 /datum/proc/save_vars()