Is your feature request related to a problem? Please describe.

Add functionality to compute percentiles over a catchment or subcatchment.

Describe the solution you'd like

ekh.catchments.percentile(river_network, field, stations, percentile=2.5, weights=area)
ekh.subcatchments.percentile(river_network, field, stations, percentile=2.5, weights=area)

Describe alternatives you've considered

No response

Additional context

No response

Organisation

No response