Hardsuit Powersink Adjustments

- Changes how hardsuit powersinks handle power draining. Uses CELLRATE now and simulates 40kW drain on whatever it is used on (might want to increase this later, it's fine on local server but may take longer to charge on main server considering lag and stuff)
- /obj/machinery can no longer be drained by default (because draining sinks and showers is amusing but doesn't make sense). Instead moved this piece of code to /obj/machinery/power, and it only works if the machine is connected via cable.
- (BONUS) Fixes one little thing in powersink (the normal one, not hardsuit module) which caused them to use more power than suposed.

Fixes (part of) #7567