i18n: add new localization strings

As always, a PR will do, localizing the new strings in the respective languages, use `npm run langs:format` to edit the localization files interactively... ``` gui.browser.sort.newest gui.browser.sort.last_updated gui.browser.sort.highest_rating gui.browser.sort.most_downloads gui.toast.title.failed_to_connect gui.toast.desc.failed_to_connect tooltip.offline ``` - [x] German - @DxsSucuk - [x] French - @Alystrasz - [x] Chinese - @KenMizz - Spanish - new maintainer possibly needed - #256