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

code/modules/fields/fields.dm

@@ -319,6 +319,8 @@
 		listeningTo = null
 
 /obj/item/multitool/field_debug/proc/on_mob_move()
+	SIGNAL_HANDLER_DOES_SLEEP
+
 	check_turf(get_turf(src))
 
 /obj/item/multitool/field_debug/process()

code/modules/fields/timestop.dm

@@ -112,6 +112,8 @@
 		unfreeze_turf(T)
 
 /datum/proximity_monitor/advanced/timestop/proc/unfreeze_atom(atom/movable/A)
+	SIGNAL_HANDLER
+
 	if(A.throwing)
 		unfreeze_throwing(A)
 	if(isliving(A))