better retry API

[xenoterracide]

I wrote this, and I don't think it even does what I mean, certainly doesn't seem like it's the same as calling exponential().attempts(...)

    const attempts = retryAttempts ?? this.props.retryAttempts
    const backoff = this.exponentialBackoff
      ? new ExponentialBackoff({
          maxAttempts: attempts,
        })
      : new ConstantBackoff(5, attempts) // for testing

    const retryPolicy = Policy.handleAll().retry().backoff(backoff).attempts(attempts)

I feel like this would be an improvement

Policy.handleAll().retry().backoffStrategy(BackoffStrategyType.EXPONENTIAL).attempts(5)