Support deployment of gitlab-sshd (gitlab-charts)

Summary

Support the use of gitlab-sshd as a component within the GitLab Shell container / chart of Cloud Native Gitlab.

Details

2020-01-1 saw the merge of gitlab-org/gitlab-shell!394 (merged), and we can now begin integration.

gitlab-sshd is designed to provide a replacement to the use of sshd from OpenSSH, and can be the single service started by a container using it.

Work items

1. Build and support configuration within gitlab-shell of the CNG containers
   • binary
   • process-wrapper / entrypoint & logging
2. Support for configuration within gitlab/gitlab-shell chart