[RFC] Automatically update the list of supported locales

[imobachgs]

Problem

#796 uses the list of locales included in the manifest.js file. Maintaining that list by hand is not an option, so we need a mechanism to do it automatically.

Solution

Add a update-manifest.py script that runs every time the PO files are imported from the agama-weblate repository.

1. The script goes through all PO files, determining the locale for each one. It assumes that the files are named as xx.po or xx_yy.po (where xx is the language and yy the territory). In the case of xx.po files, you cannot infer the territory from the name. For example, es.po corresponds to es_es.po, but uk.po corresponds to uk_ua. That's why we have a map.
2. It selects those PO files with more than 70% of translated messages.
3. It updates the manifest.json file, including the locale code (en-us) and the name of the language (English). If there is more than one locale for the same language, it includes the territory in the name (e.g., English (United Kingdom) and English (Great Britain). Otherwise, it just uses the language name (English).

Testing

• Manually tested.

To do

• Extend the map, based on the language_map.txt from the Cockpit project.
• Extend/improve the documentation
• Better error reporting

[lslezak]

Do we actaually need this mapping? The langtable provides the most common territory for a language if we do not know it from the PO file name. See https://raw.githubusercontent.com/mike-fabian/langtable/main/langtable/data/languages.xml

[imobachgs]

Oh, you are right, the territories are sorted by rank. I will fix that.

[lslezak]

Just for the record: it turned out that e.g. for "pt" the highest ranked is "pt_BR" which is actually correct from the ranking POV, but usually the "pt_PT" is the default...

[coveralls]

coverage: 75.13%. remained the same when pulling b957a6e on imobachgs:auto-update-locales into 18d7a88 on openSUSE:master.