PickleStepResult should be public

### 🤔 What's the problem you're trying to solve?

To implement a custom formatter like ProgressFormatter, you must be able to sort by Pickle Step ID. However `models.PickleStepResult` is an internal type, so this is impossible.

### ✨ What's your proposed solution?

Make PickleStepResult a public (non-internal type)

### ⛏ Have you considered any alternatives or workarounds?

N/A

### 📚 Any additional context?

Custom formatter example: https://github.com/cucumber/godog/tree/main/_examples/custom-formatter

Start by locating models.PickleStepResult and reviewing the custom formatter example in _examples/custom-formatter. Confirm how ProgressFormatter needs to access and sort by Pickle Step ID; done means PickleStepResult is publicly accessible and the formatter use case can compile and work without an internal-type restriction.

Written by the indexing model from the issue text.