Function draw_battery_icon 

pub fn draw_battery_icon<D>(
    target: &mut D,
    top_left: Point,
    metrics: &BatteryIconMetrics,
    indicator: &BatteryIndicator,
)
where
    D: DrawTarget<Color = BinaryColor>,

Draw the battery indicator with its zone’s top-left corner at top_left.

Public because it is the one piece of this module a richer, more graphical UI would want to keep and reuse verbatim.