Perl harmonized errors

[ehuelsmann]

🤔 What's changed?

Test suite for parse errors is now run too.

⚡️ What's your motivation?

Consistency. The rest is explained in #31.

🏷️ What kind of change is this?

:bug: Bug fix (non-breaking change which fixes a defect)

♻️ Anything particular you want feedback on?

I think this is a minor version at most: the only difference in behaviour is the error code path, which now results in Cucumber Messages (in most cases) instead of exceptions to be caught.

The fact that the exceptions don't auto-stringify anymore doesn't look like a major issue, because they used to be immediately stringified when being thrown (throwing and having a stringification method turn out to be incompatible).

📋 Checklist:

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

[ehuelsmann]

Changelog still to come, obviously.

[ehuelsmann]

After consulting with @mpkorstanje, he'll review in hindsight, if he wants to.