Automatically reflash corrupt ChromeBooks

[a-wai]

With #2491 fixed we now have a way to identify corrupt ChromeBooks. Those are reported daily on Slack in the #general channel. However, reflashing affected devices is done fully manually for now.

It would be nice to have a service/script able to monitor corrupt devices and automatically trigger a reflash.

Note: device flashing is currently done using the cros-flasher script, as the new KernelCI doesn't provide any mechanism/job/template for such tasks.