Resolve "AHopkins review - create two environment files"

Closes #9 (closed)

This MR addresses anders hopkins suggestions about setting two environment files when working with the notebooks (environment-docs.yml) and working with the functions themselves in src . I also removed some unecessary functions through this step as well. Tested the scripts with the new environment and worked well.

Review:

For the review, plus quickly:

1. Build environment.yml ( mamba env create -f environment.yml OR mamba env update -n hyswap-geospatial-data-assembly-env) and run the scripts in src. e.g. python src/fetch_nhdplus.py and make sure that it runs without errors (particularly ModuleErrors).
2. Build environment-docs.yml and run the two notebooks.

Note - not sure why `sample_hucs_props_tbl.csv was updated here but review can ignore that.