Add changes to seaice notebooks for new variables grid_file and path_nsidc.

[dabail10]

Description of changes:

• Have you followed the guidelines in our Contributor's Guide?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you made sure that the pre-commit checks passed (#8 in Adding Notebooks Guide)?
• Have you hidden the code cells (#8 in Adding Notebooks Guide) in your notebook?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you successfully tested your changes locally?
• Have you moved any observational data that you are using to /glade/campaign/cesm/development/cross-wg/diagnostic_framework/CUPiD_obs_data and ensured that it follows this format within that directory: COMPONENT/analysis_datasets/RESOLUTION/PROCESSED_FIELD_TYPE?

[mnlevy1981]

I don't think Hemis_seaice_visual_compare_contour.ipynb uses NSIDC data, so we don't need to set path_nsidc

[mnlevy1981]

I think grid_file and path_nsidc are repeated in the cell now?

climo_nyears = 35
grid_file = "/glade/campaign/cesm/community/omwg/grids/tx2_3v2_grid.nc"
path_nsidc = "/glade/campaign/cesm/development/cross-wg/diagnostic_framework/CUPiD_obs_data/ice/analysis_datasets/hemispheric_data/NSIDC_SeaIce_extent"

lc_kwargs = {}

hist = 0

path_nsidc = "/glade/campaign/cesm/development/pcwg/ice/data/NSIDC_SeaIce_extent"
grid_file = "/glade/campaign/cesm/community/omwg/grids/tx2_3v2_grid.nc"

If I'm reading the diff right, the second and third lines are your new additions to this notebook while the last two lines were already there from #168. It looks like I left the old default for path_nsidc (/glade/campaign/cesm/development/pcwg/ice/data/NSIDC_SeaIce_extent instead of the sudirectory of /glade/campaign/cesm/development/cross-wg/diagnostic_framework/CUPiD_obs_data that's used in the config.yml file for key_metrics); I'm all for updating to the new value, but can we either update path_nsidc where it was already declared or remove the old declarations of grid_file and path_nsidc down below?

[mnlevy1981]

LGTM!