Design and implement a translation pipeline and build automation for tours

[NathanLovato]

The tour already supports internationalization and translation string extraction (through core/translations/translation_parser.gd).

That's enough to add multiple languages to a tour, but we could use an efficient and mostly automated pipeline to extract, crowdsource, check, and integrate translations in any given tour.

This task is about first figuring out the desired pipeline and workflow, from extracting the strings, publishing them to a translation platform or a repository, getting updated files, and setting a threshold or requirements for integrating and publishing translations for a given language.

This needs to be easy to distribute and set up in individual tour repositories.

This task could draw from the work done for Learn GDScript From Zero: https://github.com/GDQuest/learn-gdscript-translations/. We'd gladly take feedback from people really experienced in this area too, on what could be improved.

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Note: we don't have the resources to implement this ticket ourselves currently, so contributions in this area are welcome.