Add quality stage with codequality failures

@tmaczukin said in !675 (comment 50634263)

Our previous fmt test was failing if code was not formatted properly. Thanks to this it was proper all the time because without it, the pipeline would not succeed. Now the pipeline was green and I've missed the Code quality degraded on 1 point message! Can we make codequality job failing on such reports?

There are plans about preventing merges in case of codequality degradation in https://gitlab.com/gitlab-org/gitlab-ee/issues/2547 but it's still not scheduled.

This MR appends a quality stage to our pipelines and ensure it fails in case of any quality issue.

I decided to move quality at the end of the pipeline in order to be able to prepare packages also in case of quality concerns.

!777 (closed) is an example of codequality failure.

/cc @ayufan