Auto Retry failed CI jobs

We have random failing tests and I am tired doing manual work by pressing Retry button constantly.

I would like to be able to specify retry_count in gitlab-ci.yml which will retry failing builds N times.

It should be something pretty simple like

if build.failed? && retries < N
  build.retry
end

We already have logic for Build retry. We only need syntax support and small piece of code to trigger it.

cc @ayufan