Print step declaration line instead of handler declaration line

[SpencerC]

🤔 What's changed?

Pretty printing results now prints the line where the step is declared instead of the line where the handler is declared.

⚡️ What's your motivation?

Printing the file and line number of handlers often produces meaningless results. For example:

• Anonymous functions: ctx.Step("...", func () {...}) always point to line 0: some_file_test.go:0
• Instance receiver methods: ctx.Step("...", instance.Method) always point to: <autogenerated>:1.

Pointing to the step declaration does require an additional click to get to the handler code, so an alternative approach would be to improve the reflection process to do a better job locating the handler code.

🏷️ What kind of change is this?

• 🏦 Refactoring/debt/DX (improvement to code design, tooling, etc. without changing behaviour)

This might be considered breaking if anyone is relying on the previous specific log format in CI tasks.

♻️ Anything particular you want feedback on?

📋 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.

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