feat: add previous attempts to Ctrf test results

[ysfaran]

This would resolve the second part of #20.

The PR adds a new field previousAttempts in case the same TestCase has multiple test results, which primarily happens if a test was flaky.

As suggested in #20 I just added minimal information to the attemps:

export interface CtrfTestAttempt {
  status: CtrfTestState
  duration: number
  message?: string
  trace?: string
  snippet?: string
}

I also added a simple test.

Let me know what you think 🙂

[Ma11hewThomas]

Thanks for this, @ysfaran.

I've been assessing how to include retry information and decided that your suggestion for the property name to be retryAttempts is a better fit than' previousAttempts'.

Otherwise, I'm happy with the change.

[ysfaran]

@Ma11hewThomas great!

I updated the commit by using the word retry instead of previous for the attempts.