Issue #3525392: Add constraint for ResponseStatus Condition status code
Issue raised on https://www.drupal.org/project/drupal/issues/3525392
The changes add a constraint for ResponseStatus Condition status code, which validates it and blocks any non-expected code.
How to test it
- Add a new status option to the "ResponseStatus" form (i.e. Code 409)
- Go to Structure > Block layout > [any region] > Place block.
- Choose a block like “Powered by Drupal”.
- Under Visibility Conditions, add Response Status.
- Check status codes: enter only valid values (200, 403, 404) — it should save fine.
- Enter the wrong code (409), and it should throw an error message

Closes #3525392
