added german translation of UI

[tlsaeger]

Fixes #1783

I have verified that this pull request:

• has no linting errors (npm run lint)
• is from a uniquely-named feature branch and has been rebased on top of the latest develop branch. (If I was asked to make more changes, I have made sure to rebase onto develop then too)
• is descriptively named and links to an issue number, i.e. Fixes #123

Hi there, as mentioned in issue #1783, I've added a german translation for the web editor. (Took longer than expected)

I sorted it in the dropdown under Portuguese to have all "Latin" languages grouped together. Hope that's ok.

[welcome]

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[release-com]

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• p5.js-web-editor
  • app-ted6ea1-p5-js-web-editor.releaseapp.io

🔧Environment Status : https://app.releasehub.com/public/Processing%20Foundation/env-61a492fa54

[tlsaeger]

I incorporated the changes suggested by @binomial0 in #1783 to further improve on the quality of the translation.

[catarak]

Thank you so much for your work on this!!!