Automatically detect missing updates to OpenAPI specs and client

[FelixTJDietrich]

Motivation

#13

Description

• Add workflow to detect if there are any changes to the OpenAPI specs and client, fail if they are not committed
• Include JavaDoc in OpenAPI specs
• Add some docstrings for testing

Issues

• Workflows don't trigger again (https://github.com/orgs/community/discussions/25702) solutions:
  • Use PAT
  • Dispatch workflows after this one finished
  • Dispatch other workflows again if it committed something

-> We just don't commit anything

[FelixTJDietrich]

Will remove the automatic commit stuff, the check will just fail if the api client has not been updated.