Add energy_usage to lamp prototype

[Honktown]

I was going to file a bug report, because lamps currently (0.17.79) use "energy_usage_per_tick" when that value is per-second. It's confusing and inaccurate (in-game uses energy_usage on prototypes to describe energy usage per tick, go figure).

I could see how removing or changing the meaning of "energy_usage_per_tick" could mess up mods (and really, it should be deprecated). My suggestion is to allow, and prefer if defined (with no requirement of energy_usage_per_tick), energy_usage.

Strangely, the only other entity which uses energy_usage_per_tick is the programmable speaker (and arithmetic and decider combinators use active_energy_usage only, and constant combinators have no energy usage fields at all).