[MIRROR] Adds SIGNAL_HANDLER and SIGNAL_HANDLER_DOES_SLEEP to prevent signal callbacks from blocking (#430)

* Adds SIGNAL_HANDLER and SIGNAL_HANDLER_DOES_SLEEP to prevent signal callbacks from blocking (#52761)

Adds SIGNAL_HANDLER, a macro that sets SHOULD_NOT_SLEEP(TRUE). This should ideally be required on all new signal callbacks.

Adds BLOCKING_SIGNAL_HANDLER, a macro that does nothing except symbolize "this is an older signal that didn't necessitate a code rewrite". It should not be allowed for new work.

This comes from discussion around #52735, which yields by calling input, and (though it sets the return type beforehand) will not properly return the flag to prevent attack from slapping.

To fix 60% of the yielding cases, WrapAdminProcCall no longer waits for another admin's proc call to finish. I'm not an admin, so I don't know how many behinds this has saved, but if this is problematic for admins I can just make it so that it lets you do it anyway. I'm not sure what the point of this babysitting was anyway.

Requested by @optimumtact.
Changelog

cl
admin: Calling a proc while another admin is calling one will no longer wait for the first to finish. You will simply just have to call it again.
/cl

* Adds SIGNAL_HANDLER and SIGNAL_HANDLER_DOES_SLEEP to prevent signal callbacks from blocking

Co-authored-by: Jared-Fogle <35135081+Jared-Fogle@users.noreply.github.com>

code/game/objects/structures/stairs.dm

@@ -117,6 +117,8 @@
 		T.ChangeTurf(/turf/open/transparent/openspace, flags = CHANGETURF_INHERIT_AIR)
 
 /obj/structure/stairs/proc/on_multiz_new(turf/source, dir)
+	SIGNAL_HANDLER
+
 	if(dir == UP)
 		var/turf/open/transparent/openspace/T = get_step_multiz(get_turf(src), UP)
 		if(T && !istype(T))

code/game/objects/structures/tables_racks.dm

@@ -279,6 +279,8 @@
 	RegisterSignal(I, COMSIG_MOVABLE_MOVED, .proc/RemoveItemFromTable) //Listen for the pickup event, unregister on pick-up so we aren't moved
 
 /obj/structure/table/rolling/proc/RemoveItemFromTable(datum/source, newloc, dir)
+	SIGNAL_HANDLER
+
 	if(newloc != loc) //Did we not move with the table? because that shit's ok
 		return FALSE
 	attached_items -= source