Added infinite equivalent megacell (#93503)

## About The Pull Request
Added an infinite capacity megacell with the same logic as the power
cell equivalent. Both code and sprite is updated.
<img width="32" height="32" alt="icellbig"
src="https://github.com/user-attachments/assets/d80e71ff-4b62-4317-adaa-01dde287960a"
/>
## Why It's Good For The Game
It helps long rounds of debugging when you just want to smack an
infinite capacity megacell into the SMES for infinite power.
## Changelog
🆑
add: New item "Infinite Capacity Megacell added, which can be used for
infinite power in the SMES.
/obj/item/stock_parts/power_store/battery/infinite
/🆑

code/modules/power/battery.dm

@@ -77,3 +77,14 @@
 
 /obj/item/stock_parts/power_store/battery/crap/empty
 	empty = TRUE
+
+/obj/item/stock_parts/power_store/battery/infinite
+	name = "infinite-capacity megacell"
+	desc = "A transdimensional megacell with an inexhaustible capacity."
+	icon_state = "icellbig"
+	maxcharge = INFINITY
+	chargerate = INFINITY
+	ratingdesc = FALSE
+
+/obj/item/stock_parts/power_store/battery/infinite/use(used, force = FALSE)
+	return TRUE