ENH: Allow restoring of old versions of entities in the WebUI

Summary

The Version Info (full history) modal is extended with buttons for restoring the various versions.

Test Environment

Try it out in a server instance with an entity with at least one old version.

• fix unit test

Check List for the Author

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• All automated tests pass
• Reference related Issues
• Up-to-date CHANGELOG.md
• Annotations in code (Gitlab comments)
  • Intent of new code
  • Problems with old code
  • Why this implementation?

Check List for the Reviewer

• I understand the intent of this MR
• All automated tests pass
• Up-to-date CHANGELOG.md
• The test environment setup works and the intended behavior is reproducible in the test environment
• In-code documentation and comments are up-to-date.
• Check: Are there spezifications? Are they satisfied?

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