WIP: reintegrate L2/L3 notebooks from originals

[itcarroll]

The notebooks in this commit were originally brought into this repository in 7682ae9, but have since diverged from the author's intent. Let's try again.

[itcarroll]

I've updated the PR to reflect changes in main, in preparation for revisiting how to re-include these notebooks.

There are two L2 notebooks that were merged and modified in creating modis-explore-l2, which uses the same example datasets. Are the original techniques noted below needed in tutorials?

• download_read_visualize_L2_products
  • downloads from OB.DAAC using the APPKEY -> dowload with earthaccess
  • reads with netCDF4 -> removed in favor of xarray
  • uses cartopy axis low-level formatters directly for lat/lon -> uses cartopy axis gridlines
• read_plot_L2_chlorophyll_map_with_xarray
• uses cartopy axis low-level formatters directly for lat/lon -> uses cartopy axis gridlines

There is one L3 notebook (L3_files_read_plot) that was modified in creating modis-explore-l3. It uses some of the same techniques from the L2 notebooks and does not include additional new techniques or datasets.