Function construct_custom_netdir_with_params 

pub fn construct_custom_netdir_with_params<F, P, PK>(
    func: F,
    params: P,
    lifetime: Option<Lifetime>,
) -> BuildResult<PartialNetDir>
where
    F: FnMut(usize, &mut NodeBuilders, &mut MdConsensusBuilder),
    P: IntoIterator<Item = (PK, i32)>,
    PK: Into<String>,

As construct_custom_network(), but return a PartialNetDir, and allow network parameter customisation.