Function widest_path_with_mode 

pub fn widest_path_with_mode(
    graph: &Graph,
    from: VertexId,
    to: VertexId,
    weights: &[f64],
    mode: DijkstraMode,
) -> IgraphResult<Option<(Vec<VertexId>, Vec<EdgeId>)>>

Widest path with mode selection. Mirrors widest_path but lets you pick OUT/IN/ALL traversal on directed graphs.

Counterpart of igraph_get_widest_path(_, _, _, from, to, weights, mode).