Option to hide the recharge icon from roboport entities

[Earendel]

It would be nice to be able to hide the blinking battery icon from roboport entities.

Also the icon was appearing even while the prototype had
recharge_minimum = "0kJ"
and
energy_source.buffer_capacity = "10kJ"
so if it is only supposed to appear when buffered energy is < recharge_minimum then that is now working as expected (at least not with a 0 recharge_minimum, maybe 0 values are ignored?).

[Bilka]

Okay, added RoboportPrototype::render_recharge_icon for 2.0.67.