merge dev into main.

[birkin]

• Improves language-sorting; adds a test.
• Addresses issue https://github.com/Brown-University-Library/usepweb_project/issues/59.
  • @emylonas updated the language codes in a previous deploy; this specifically addresses sorting.
• @atbradley...
  • main work was converting dict to collection.OrderedDict in a few places.
  • example of old language-sorting: https://library.brown.edu/projects/usep/collections/MI.AA.UM.KM/ (See the "Jump to..." section)
  • example of new language-sorting: https://dlibwwwcit.services.brown.edu/projects/usep/collections/MI.AA.UM.KM/

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