Make PromptLogger show the count of failed tasks (500USD Bounty)

[lihaoyi]

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From the maintainer Li Haoyi: I'm putting a 500USD bounty on this issue, payable by bank transfer on a merged PR implementing this.

See https://github.com/orgs/com-lihaoyi/discussions/6 for other bounties and the terms and conditions that bounties operate under

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Currently it shows completed tasks via [19459/19459], but with no indication how many of those are failures, until the command completes and all failures are shown at the end. Showing the failed tasks e.g. [19459/19459, 5 failed] would help make the state of the ongoing job clear to anyone reading the prompt, both for interactive use and in CI, and give early indication that a build has failed and it's worth looking through the logs to find the failure

[chaitanyawaikar]

I would like to attempt this issue.