Add a `rerun` option even if the test is successful

[chouetz]

Hello 👋🏽 !

I wanted to check if you thought it would be interesting to add an option to gotestsum that would allow you to rerun a test even if it's not failing.
The idea is to rerun every new test several times to try and detect potential low-level flaky failures in advance.

If you find this useful, I can try to implement it.

Thanks in advance!