Adds button and switch sounds when using machinery (#8195)

code/modules/power/apc.dm

@@ -78,6 +78,7 @@
 	use_power = 0
 	req_access = list(access_engine_equip)
 	gfi_layer_rotation = GFI_ROTATION_DEFDIR
+	clicksound = "switch"
 	var/area/area
 	var/areastring = null
 	var/obj/item/cell/cell

code/modules/power/smes.dm

@@ -25,6 +25,7 @@
 	density = 1
 	anchored = 1
 	use_power = 0
+	clicksound = "switch"
 
 	var/capacity = 5e6 // maximum charge
 	var/charge = 1e6 // actual charge