This PR adds a translation for German `de_DE`.
Additionally it excludes all `*.po` files from the typos CI action.
Some comments on the decisions I made (open to discuss them):
- I choosed to use `du` instead of `Sie` as this seems appropriate
to me.
- I added `Window` (`Fenster` in German) to all split commands
as it appears more naturally to me.
Sets the LANGUAGE environment variable based on the preferred languages
as reported by NSLocale.
macOS has a concept of preferred languages separate from the system
locale. The set of preferred languages is a list in priority order
of what translations the user prefers. A user can have, for example,
"fr_FR" as their locale but "en" as their preferred language. This would
mean that they want to use French units, date formats, etc. but they
prefer English translations.
gettext uses the LANGUAGE environment variable to override only
translations and a priority order can be specified by separating
the languages with colons. For example, "en:fr" would mean that
English translations are preferred but if they are not available
then French translations should be used.
To further complicate things, Apple reports the languages in BCP-47
format which is not compatible with gettext's POSIX locale format so
we have to canonicalize them. To canonicalize the languages we use
an internal function from libintl. This isn't normally available but
since we compile from source on macOS we can use it. This isn't
necessary for other platforms.
