Function align_edges_to_blues 

fn align_edges_to_blues(
    axis: &mut Axis,
    metrics: &ScaledAxisMetrics,
    group: ScriptGroup,
    scale: &Scale,
) -> Option<usize>

Align horizontal edges to blue zones.

See https://gitlab.freedesktop.org/freetype/freetype/-/blob/57617782464411201ce7bbc93b086c1b4d7d84a5/src/autofit/aflatin.c#L3030