Include time executing user code in summary

[davidjgoss]

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

From #35 (review):

The existing cucumber-js summary provides an extra timing metric of "time executing steps" (which I think is better expressed as "time executing your code" to account for hooks)

✨ What's your proposed solution?

Grab all test step results (for actual test steps and for test run hooks), sum up the durations, and append (1m 4s executing your code) to the timing line of the summary.

⛏ Have you considered any alternatives or workarounds?

No response

📚 Any additional context?

No response