Features/#450 add metadata kh

[khelfen]

Fixes #450 partly . Depends on #568 .

Before merging into dev-branch, please make sure that

• [ ] ~the CHANGELOG.rst was updated.~
• [x] new and adjusted code is formated using black and isort.
• [ ] ~the Dataset-version is updated when existing datasets are adjusted.~
• [ ] ~the branch was merged into the continuous-integration/run-everything-over-the-weekend-branch.~
• [x] the workflow is running successful in test mode.
• [ ] the workflow is running successful in Everything mode.