Prepare a script to check whether all of the features come from a predefined list

[krystian-hebel]

The problem you're addressing (if any)

The script should be created with CI in mind. This check could be added to scripts created in #876, to do both checks at once. There would be 3 main reasons for this script:

• check whether test definition and JSON file are in sync
• verify there are no typos in feature names
• ensure that new features aren't freely added

This task also includes changes to the documentation, namely adding-and-naming-test-cases.md.

Describe the solution you'd like

Deliverable: PR with the script that can be started manually, no need for adding it to CI at this point as it would surely fail.

Where is the value to a user, and who might that user be?

No response

Describe alternatives you've considered

No response

Additional context

No response