Add hierarchical options to calculations

[zachary-foster]

Also add "long" as an output format since that is better at storing the hierarchy information.

• [ ] calc_group_median
• [ ] calc_group_rsd
• [ ] calc_group_stat
• [ ] calc_n_samples
• [ ] calc_obs_props
• [ ] calc_prop_samples
• [ ] calc_taxon_abund
• [ ] compare_groups
• [ ] counts_to_presence
• [ ] rarefy_obs
• [ ] zero_low_counts