Function price_axis_width 

pub fn price_axis_width(
    painter: &Painter,
    price_map: &PriceMap,
    tag_labels: &[&str],
    formatter: Option<&dyn PriceFormatter>,
) -> f32

Width of the current price labels and tags, including their plot gap and right clearance. Include formatted session and volume labels in tag_labels when allocating their column, and the host formatter the labels are written with.