Make ref table function way simpler and more efficient

[ehinman]

I realized I initially built the reference table function to match dataRetrieval, thinking that there was a reason we couldn't reuse the get_ogc_data() function, but I think this is inefficient and incorrect. Swapped out the repeated code for get_ogc_data and changed the "id" column to the singular subject name of the reference table, e.g. "site-type-codes" has the "id" column changed to "site_type_code" (the rest of the columns swap underscores for dashes, so keeping consistent).

I also learned that if there aren't any geometries present in the dataframe, geopandas will simply return a pandas DataFrame. This avoids the issue I created in the last MR where I thought I had to specify "no geopandas" to get back a regular dataframe, and the logger was yelling about geopandas not being installed due to my oversight.

The only risk is that URLs contain the argument skipGeometry=FALSE, like this:
https://api.waterdata.usgs.gov/ogcapi/v0/collections/time-zone-codes/items?skipGeometry=False&limit=50000

However, it doesn't seem to actually affect what comes back.

[ehinman]

@thodson, @jzemmels, can one of you take a look at this PR this week?

[jzemmels]

Changes look good. Just one minor typo in the example and a question about dependencies. Otherwise approved.

[jzemmels]

Are these new dependencies from the changes made in this PR?
I don't see docutils or mapclassify used explicitly in the package files anywhere (from a CTRL + ALT + F through the package files)

[ehinman]

docutils is one of the dependencies for building the documentation, and they made some update to the latest version that breaks the pipeline. Keeping it at an earlier version while the other packages catch up seems to fix it for now.

The other dependencies are needed to use the gpd.explore() interactive mapping functionality of geopandas, and are not installed if you simply pip install geopandas. The waterdata demo notebook I merged in earlier this week uses gpd.explore() and currently shows errors in the Jupyter notebook in the documentation: https://doi-usgs.github.io/dataretrieval-python/examples/WaterData_demo.html

[thodson-usgs]

Nice in the work! In future, the docutils issue would be better as a separate PR.