Generate HTML error report artifact for Robo test

[AaronMT]

Our CI captures artifacts generated from Flank. For instrumentation, the generated report from ReportManager.kt is fine. It would be great if it can also be adjusted to accommodate Robo test results. Perhaps a summary report table of failed devices and links to the matrix is suffice. One less click required to copy and paste the matrix web links out of logs would be great.

https://github.com/Flank/flank/blob/master/test_runner/src/main/kotlin/ftl/reports/util/ReportManager.kt#L44