Metadata directories were renamed while adding store descriptions into
strings files for simplicity.
This interferes with releases so is released.
An hardcoded lookup table is used instead.
This makes translation easier as there's a single file to edit at.
Existing short and full descriptions are conserved.
sync_translations.py takes care of updating the metadata files.
The metadata directories are renamed to match the language codes used in `res/`.
Contributing guidelines are updated accordingly.
`gen_layouts.py` lists the layouts in `res/xml` and generate the
`pref_layout_values` and `pref_layout_entries` arrays into
`res/values/layouts.xml`.
These arrays are hard to maintain as the order has to match, which is
fragile.
This relies on every layouts having a `name` attribute.
The new script makes sure that strings files don't contain obsolete
strings but also ease the job of contributors by adding missing
translations as comments.
A Github Action ensures that translations stay in sync over time.
