fix(hooks): wrap errors to preserve sentinel values

[victoriacheng15]

🤔 What's changed?

This PR fixes hook error wrapping to preserve the types of all merged errors.

Specifically:

• Introduces a custom joinedError type and mergeErrors helper at the end of suite.go.
• Updates runBeforeStepHooks, runAfterStepHooks, runBeforeScenarioHooks, and runAfterScenarioHooks in suite.go to use mergeErrors instead of fmt.Errorf("%v, %w").
• This ensures that all errors returned from hook handlers are correctly wrapped, making them fully detectable by errors.Is and errors.As.

Backward Compatibility:

• Go 1.18 - 1.19: Supported via the custom Is and As methods on joinedError, which have been natively supported by the standard errors package since Go 1.13.
• Go 1.20+: Supported via the Unwrap() []error method, allowing modern Go runtimes and static analysis tools to natively unwrap the error slice.
• Error Messages: Preserves the original %v, %v string formatting, ensuring no breaking changes to logs or output formatting.

⚡️ What's your motivation?

Fixes #732

Currently, when a step fails and a hook also returns an error (such as a skip), they are merged using fmt.Errorf("%v, %w"). This prevents errors.Is and errors.As from detecting the hook error type because it is formatted with %v instead of %w. As a result, the runner fails to recognize sentinel errors like ErrSkip returned from hooks when a step fails.

🏷️ What kind of change is this?

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

♻️ Anything particular you want feedback on?

Feedback on the joinedError implementation for Go versions < 1.20 (which do not support multiple %w verbs).

📋 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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