Fixes some shielded component jank (#79674)

## About The Pull Request

If you attempted to use the shielded component properly (applying it in
`Init`), it would not work because the equipped signal was improperly
passing its arguments to `set_wearer`.

The only reason why this worked now is that every consumer added the
component after it was `equipped`... usually in `equipped`.

This also meant shielded items that added it in equipped were open to an
exploit, allowing you to reset the charges by unequip / re-equip.

## Changelog

🆑 Melbert
fix: Fixes some potential exploits and issues involving shielded
equipment.
/🆑

code/datums/components/shielded.dm

@@ -3,6 +3,7 @@
  */
 
 /datum/component/shielded
+	dupe_mode = COMPONENT_DUPE_UNIQUE
 	/// The person currently wearing us
 	var/mob/living/wearer
 	/// How many charges we can have max, and how many we start with
@@ -113,7 +114,7 @@
 	if((slot & ITEM_SLOT_HANDS) && !shield_inhand)
 		lost_wearer(source, user)
 		return
-	set_wearer(source, user)
+	set_wearer(user)
 
 /// Either we've been dropped or our wearer has been QDEL'd. Either way, they're no longer our problem
 /datum/component/shielded/proc/lost_wearer(datum/source, mob/user)
@@ -125,6 +126,11 @@
 		wearer = null
 
 /datum/component/shielded/proc/set_wearer(mob/user)
+	if(wearer == user)
+		return
+	if(!isnull(wearer))
+		CRASH("[type] called set_wearer with [user] but [wearer] was already the wearer!")
+
 	wearer = user
 	RegisterSignal(wearer, COMSIG_ATOM_UPDATE_OVERLAYS, PROC_REF(on_update_overlays))
 	RegisterSignal(wearer, COMSIG_QDELETING, PROC_REF(lost_wearer))

code/modules/antagonists/cult/cult_items.dm

@@ -377,8 +377,15 @@ Striking a noncultist, however, will tear their flesh."}
 	fire = 50
 	acid = 60
 
-/obj/item/clothing/suit/hooded/cultrobes/cult_shield/setup_shielding()
-	AddComponent(/datum/component/shielded, recharge_start_delay = 0 SECONDS, shield_icon_file = 'icons/effects/cult/effects.dmi', shield_icon = "shield-cult", run_hit_callback = CALLBACK(src, PROC_REF(shield_damaged)))
+/obj/item/clothing/suit/hooded/cultrobes/cult_shield/Initialize(mapload)
+	. = ..()
+	AddComponent( \
+		/datum/component/shielded, \
+		recharge_start_delay = 0 SECONDS, \
+		shield_icon_file = 'icons/effects/cult/effects.dmi', \
+		shield_icon = "shield-cult", \
+		run_hit_callback = CALLBACK(src, PROC_REF(shield_damaged)), \
+	)
 
 /// A proc for callback when the shield breaks, since cult robes are stupid and have different effects
 /obj/item/clothing/suit/hooded/cultrobes/cult_shield/proc/shield_damaged(mob/living/wearer, attack_text, new_current_charges)

code/modules/capture_the_flag/ctf_equipment.dm

@@ -207,12 +207,18 @@
 	var/lose_multiple_charges = TRUE
 	var/show_charge_as_alpha = TRUE
 
-/obj/item/clothing/suit/armor/vest/ctf/equipped(mob/user, slot)
+/obj/item/clothing/suit/armor/vest/ctf/Initialize(mapload)
 	. = ..()
-	if(!slot || slot & ITEM_SLOT_HANDS)
-		return
-	AddComponent(/datum/component/shielded, max_charges = max_charges, recharge_start_delay = recharge_start_delay, charge_increment_delay = charge_increment_delay, \
-	charge_recovery = charge_recovery, lose_multiple_charges = lose_multiple_charges, show_charge_as_alpha = show_charge_as_alpha, shield_icon = team_shield_icon)
+	AddComponent( \
+		/datum/component/shielded, \
+		max_charges = max_charges, \
+		recharge_start_delay = recharge_start_delay, \
+		charge_increment_delay = charge_increment_delay, \
+		charge_recovery = charge_recovery, \
+		lose_multiple_charges = lose_multiple_charges, \
+		show_charge_as_alpha = show_charge_as_alpha, \
+		shield_icon = team_shield_icon, \
+	)
 
 // LIGHT SHIELDED VEST
 

code/modules/clothing/suits/_suits.dm

@@ -17,10 +17,6 @@
 	var/blood_overlay_type = "suit"
 	limb_integrity = 0 // disabled for most exo-suits
 
-/obj/item/clothing/suit/Initialize(mapload)
-	. = ..()
-	setup_shielding()
-
 /obj/item/clothing/suit/worn_overlays(mutable_appearance/standing, isinhands = FALSE)
 	. = ..()
 	if(isinhands)
@@ -47,12 +43,3 @@
 	if(ismob(loc))
 		var/mob/M = loc
 		M.update_worn_oversuit()
-
-/**
- * Wrapper proc to apply shielding through AddComponent().
- * Called in /obj/item/clothing/Initialize().
- * Override with an AddComponent(/datum/component/shielded, args) call containing the desired shield statistics.
- * See /datum/component/shielded documentation for a description of the arguments
- **/
-/obj/item/clothing/suit/proc/setup_shielding()
-	return