Auto DevOps deployment

Closes #1

Since this will use cronjob which Auto DevOps was not exactly designed for it will unfortunately require forking a couple of things.

Firstly it will require forking auto-deploy-app helm chart as this chart is almost entirely designed for web apps with an HTTP endpoint.

Then it will require forking the .gitlab-ci.yml we use in Auto DevOps until such time as we merge and release https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/28130 which is likely going to be %12.0 .

Also note I've configured a K8s cluster for this project which was set up on gitlab-internal GCP project. I know it's not necessarily the clearest named and I set it up for a different project but in the interest of not wasting money on lots of Kubernetes clusters we may as well re-use it for now.

In the nearish term 🤞 we'll have a cluster set up on gitlab-org group level that can be used by anyone and this would be a little less hacky . Or we'll have an instance wide cluster (https://gitlab.com/gitlab-org/gitlab-ce/issues/59668) which will also do the trick.

TODO

• Configure review CI variable K8S_SECRET_GITLAB_API_TOKEN with environment scope review/* using new account review-gitlab-slack-archivist
• Configure review CI variable K8S_SECRET_SLACK_API_TOKEN with environment scope review/*
• Do deployment confirm it's working from the review app
• Set all the production K8S_SECRET_* with environment scope production

I've also set PERFORMANCE_DISABLED, DAST_DISABLED as these jobs are only applicable to web applications that can be tested from the outside via HTTP requests.