Cropping extent for `process_*`

[mitchellmanware]

• [ ] process_flatten_sds
• [ ] process_modis_merge
• [ ] process_bluemarble
• [ ] process_modis_swath
• [x] process_koppen_geiger
• [x] process_nlcd
• [x] process_ecoregion
• [ ] process_tri
• [ ] process_nei
• [x] process_sedac_population
• [x] process_sedac_groads
• [x] process_hms
• [x] process_gmted
• [x] process_narr
• [x] process_geos
• [x] process_merra2
• [x] process_gridmet
• [x] process_terraclimate
• [x] process_huc
• [ ] process_cropscape
• [ ] process_prism
• [ ] process_olm