[MIRROR] Makes update_icon_updates_onmob more robust [MDB IGNORE] (#21076)

* Makes update_icon_updates_onmob more robust (#75324)

Safeguards against #74965 happening in the future.

Noticed a bunch of these were using ITEM_SLOT_HANDS. This is incorrect,
as the element already automatically updates held items. grep'd it to
catch future instances.

Likewise, a number of objects weren't passing slot_flags to the element,
meaning it wasn't actually updating those things properly when they were
being worn. I've simplified this so now the element will automatically
update all slot_flags, and passing an additional slot to the element
when being added is only needed for additional slots that might need to
be updated. This also means if slot_flags change, the element will now
update correctly as well.

🆑 ShizCalev
code: The update_icon_updates_onmob element will now automatically
update all slots in an item's slot_flags var. This does fix multiple
things that weren't updating properly. Passing a slot to the element is
now only necessary if you want to add additional slots to be updated.
/🆑

* Makes update_icon_updates_onmob more robust

---------

Co-authored-by: ShizCalev <ShizCalev@users.noreply.github.com>

code/game/objects/items/rcd/RCL.dm

@@ -27,7 +27,7 @@
 
 /obj/item/rcl/Initialize(mapload)
 	. = ..()
-	AddElement(/datum/element/update_icon_updates_onmob, ITEM_SLOT_HANDS)
+	AddElement(/datum/element/update_icon_updates_onmob)
 	AddComponent(/datum/component/two_handed, wield_callback = CALLBACK(src, PROC_REF(on_wield)), unwield_callback = CALLBACK(src, PROC_REF(on_unwield)))
 
 /// triggered on wield of two handed item