Recharger QoL Tweaks (#3826)

changes:

Rechargers now briefly show a progress bar showing the current charge level of the device currently charging.
Examining a recharger will now specify what is in the charger.
Atoms can now mark themselves as requiring an icon update on initialize instead of overriding Initialize() just to call update_icon().
Charger code is now slightly more modular, using proc/get_cell() to get a ref to the power cell instead of hard-coded if-else chains for each supported type.

code/game/objects/items.dm

@@ -75,6 +75,8 @@
 
 	var/icon_override  //Used to override hardcoded clothing dmis in human clothing pr
 
+	var/charge_failure_message = " cannot be recharged."
+
 /obj/item/Destroy()
 	if(ismob(loc))
 		var/mob/m = loc
@@ -84,9 +86,13 @@
 		src.loc = null
 	return ..()
 
+
 /obj/item/device
 	icon = 'icons/obj/device.dmi'
 
+/obj/item/proc/get_cell()
+	return DEVICE_NO_CELL
+
 //Checks if the item is being held by a mob, and if so, updates the held icons
 /obj/item/proc/update_held_icon()
 	if(ismob(src.loc))