Internationalize the UI and add a German localization

[bearn01d]

As discussed with @SebastianOpriel and @richardtreier, we as Fraunhofer FIT provide an internationalization of the UI alongside a German translation as a PR, as part of the project Datenraum Kultur.

The flag icons used for the English and German localization are taken from here and here, respectively. For both images, the licensing information states that they are in the public domain.

Looking forward to your feedback!

Checklist

Beta Give feedback

1. The PR title is short and expressive.
2. I have updated the CHANGELOG.md. See changelog_update.md for more information.
3. I have performed a self-review

[tmberthold]

Hello and thank you for the contribution! 🚀

We will let you know as soon as we know when this cool feature will be on our product roadmap (@AbdullahMuk).

[kulgg]

Cool PR! We should merge this as soon as possible. The longer we wait the more merge conflicts will be present. @AbdullahMuk

[richardtreier]

Thank you for your contribution. I apologize for the delayed merge. We've been on a very tight schedule to deliver the upcoming release, thus we could not afford to incorporate this PR into the code base yet.

For the upcoming release (tomorrow) I also do not foresee that we'll have the time to include this.

I recommend we do it after that release.

[bearn01d]

Thank you for the update, @richardtreier. With @AbdullahMuk, it has been discussed that just before you start the review, we will rebase this branch onto the latest main code to resolve the piled up merge conflicts from the last weeks.

[bearn01d]

I force pushed a rebased version of this feature, resolving the conflicts by accepting all changes made by you in a first step. This is not ready for review yet, because we need to re-add some translations that have to be integrated differently now and add some new translations.

[richardtreier]

I'll go ahead and migrate this code to work with our latest changes.

[richardtreier]

@bearn01d

Hello, I am currently in the progress of refreshing this PR and getting ready to merge.

I see some issues with trying to use the "classic" Apache 2.0 license header comments in the files touched by the PR.

I would like to switch to a NOTICE-file style attribution + copyright: https://infra.apache.org/licensing-howto.html#example-notice, to avoid issues with comments in the multiple file formats, e.g. rendering in DOM, etc.

My suggestion would be:

sovity EDC UI
Copyright (c) 2024. sovity GmbH

This product includes software developed at sovity GmbH (https://www.sovity.de).
Copyright (c) 2024. sovity GmbH

The Initial Internalization of the EDC UI to German was implemented by the
Fraunhofer Institute for Applied Information Technology FIT (https://www.fit.fraunhofer.de/).
Copyright (c) 2024. Fraunhofer Institute for Applied Information Technology FIT

Is that okay with you?