ENH: add YAMLFileConverter

Summary

Create converter for YAML files.

Test Environment

unit tests

In the tests "broken_json" meant that the json did not comply with a given schema. I renamed this to "invalid" and added "broken" cases, where the file does not comply with the JSON/YAML syntax.

Check List for the Author

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• All automated tests pass
• Reference related issues
• Up-to-date CHANGELOG.md (or not necessary)
• 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 (or not necessary)
• The test environment setup works and the intended behavior is reproducible in the test environment
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• Check: Are there specifications? Are they satisfied?

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