Add localization for UI strings in German

[stepankuzmin]

Hey 👋

This PR adds translations for UI strings we use in GL JS into German. We translated the UI strings automatically using the Google Translate API, and we need to verify that the translation is correct.

To help us verify the translations, you can open the Files changed tab on this page and compare the translations with the original file src/ui/default_locale.js.

If the translation looks good, you can approve it using the Review changes button in the Files changed tab and selecting the Approve radio button when submitting the review.

To improve the machine translation, you can click the plus sign next to the line you want to enhance and select the suggestion button on the toolbar.

After making the suggestions, you can mark the review as finished using the Review changes button and selecting the Request changes radio button.

Thanks for helping 🙌

[kkaefer]

This translation uses the formal “Sie”. A less formal translation is probably okay in most contexts as well. An alternative could be to offer a formal and an informal translation and let users select.

[kkaefer]

There’s no commonly used abbreviation for this. The full word is “Fuß”

[sebrockm]

True, but I think that is due to the fact that it is this unit which is not commonly used in the first place, so it's abbreviation isn't either. If however, "Fuß" happens to be used as a unit in German, then I think ft would be the correct abbreviation. Actually, abbreviation is not the correct term here, I think. It rather is a symbol that happens to be an abbreviation in this case. Consider e.g. cm or µm which are not really abbreviations for Zentimeter or Mikrometer. German Wikipedia also uses ft and calls it "Einheitenzeichen".

[stepankuzmin]

I think we'll switch to the Intl.NumberFormat in the future and use the user's locale to format the units. So I think we can use ft for now