feature 1684 use case HSS s2s

[j-opatz]

Pull Request Testing

• Describe testing already performed for these changes:
  This is a similar use case to the BSS, CFSv2 s2s use case that was just entered into develop. The use case was checked to be running correctly. The updates that occured from the BSS use case have been merged with this one, so there shouldn't be any conflicting issues.

• Recommend testing for the reviewer(s) to perform, including the location of input datasets, and any additional instructions:
  Check that you can run the use case (use the ice_cover environment on Seneca if needed or any with the netcdf4 package), data is under /d1/projects/METplus/METplus_Data, and that documentation looks correct. The build should be fine, with the only errors being new data.
  the new documentation can be looked at here:https://metplus.readthedocs.io/en/feature_1684_usecase_hss_s2s/generated/model_applications/s2s/GridStat_fcstCFSv2_obsGHCNCAMS_MultiTercile.html#sphx-glr-generated-model-applications-s2s-gridstat-fcstcfsv2-obsghcncams-multitercile-py

• Do these changes include sufficient documentation updates, ensuring that no errors or warnings exist in the build of the documentation? [Yes]

• Do these changes include sufficient testing updates? [Yes]

• Will this PR result in changes to the test suite? [Yes]
  
  If yes, describe the new output and/or changes to the existing output:
  As before, a develop-ref update will be required.

• Please complete this pull request review by [7/11].
  

Pull Request Checklist

See the METplus Workflow for details.

• Add any new Python packages to the METplus Components Python Requirements table.
• Review the source issue metadata (required labels, projects, and milestone).
• Complete the PR definition above.
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• Close the linked issue and delete your feature or bugfix branch from GitHub.

[CPKalb]

I couldn't find the documentation for the use case, but it ran successfully for me on seneca

[CPKalb]

Use case ran as expected. Should there be a space between GHCN and CAMS in the documentation?