Allow failling the check without failling to step.

[gpoulin-hopper]

Currently if fail_below_threshold is true and the threshold, both the step and the coverage check would be marked as failed. Ideally only the check would be marked as failed since it allows to easily that the job was able to succeed, but the coverage was insufficient. To avoid changing the current behaviour, an input could be added to get the described behaviour.

A workaround is to set continue-on-error: true. However this solution will also mark the job as success even if we were unsuccessful at creating the coverage report.