Update build system/scripts to allow continual translation of the website

[MattBlissett]

This PR modifies the website build script to generate the "List of terms" (DWC and the three vocabularies) and the Quick-Reference Guide documents in other languages.

Demo site:

• List of terms in French
• Establishment Means in French
• Quick Reference Guide in French
• (Note the non-term parts of the pages have been semi-auto-translated by me, pending integration of this content with Crowdin, and many French pages are missing on the demo site. The missing Dublin Core terms in French is because they've not been enabled for translation in Crowdin, I'll fix that.)

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In more detail:

Translation of Darwin Core terms and vocabularies into French and Czech is complete using the CrowdIn system. The translations appear in the rs.tdwg.org repository at https://github.com/tdwg/rs.tdwg.org/blob/master/terms/terms-translations.csv and similar locations for the vocabularies.

With this PR the English site is unchanged except for

• some irrelevant whitespace changes
• some out-of-date definitions still in the QRG are now up-to-date
• "duplicate" term names are not excluded from the index of terms, since they are not duplicates — e.g. dwc:TaxonID and dwc:taxonID are different terms.

However, there are significant changes to the build scripts:

1. Remove obsolete scripts
2. Rename and rearrange (and update READMEs) build scripts/templates for clarity and to allow easier integration with Crowdin
3. Rework the main script to build all five outputs (DWC-list, EM-list, DOE-list, pathway-list, QRG) in all languages without requiring manual modification.
   a. So I moved the QRG from being generated from the CSV stored in this repository by a separate script to using same script and data as the others.
4. Create a Github workflow to run that script. I expect to set this up to run frequently, e.g. whenever there are changes to translations.

With manual changes to the configuration, the script is still capable of building the existing English pages as part of the process to make a new release of DWC.

The translations can include all current pages, but I have not planned to translate old versions of the documents like https://dwc.tdwg.org/list/2023-09-13. Translating pages like the RDF guide is optional.

Still to do:

1. Add the page templates and whole pages (e.g. homepage and other guides) to Crowdin, so they can be translated and kept up-to-date. I'll wait for approval before doing this — I would merge an English-only version of these changes, set up the Crowdin integration for at least French and Czech, then enable generation of the site in those languages.

Closes #242.

Please do not merge — my nonsense French must be removed first!