Add testdata where steps are prefixes of other steps

[mpkorstanje]

⚡️ What's your motivation?

Verify which implementations are affected by #400

🏷️ What kind of change is this?

• 🐛 Bug fix (non-breaking change which fixes a defect)

📋 Checklist:

• I agree to respect and uphold the Cucumber Community Code of Conduct
• I've changed the behaviour of the code
  • I have added/updated tests to cover my changes.
• My change requires a change to the documentation.
  • I have updated the documentation accordingly.
• Users should know about my change
  • I have added an entry to the "Unreleased" section of the CHANGELOG, linking to this pull request.

[obligaron]

Are the newly added .ndjson files valid?

While working on #405, I used the test data.
However, they failed for the current .NET Spec/UnitTest implementation because the test infrastructure expects the test data to contain only one JSON object per line.
For my pull request, I manually changed the test data.

Should we adjust the files or change the .NET Spec/UnitTest implementation?

[mpkorstanje]

Ah, no that's my bad! Should be a single line. Though for this repository I wouldn't expect the test suite to interact with the data. Other than through make.

[obligaron]

The .NET tests only read the test data. Currently, they fail if the data is not formatted correctly. I opened issue #406 to make the .NET implementation more robust.