Create a PR to add our official GitLab charts to Helm stable repo

There is an official Helm repository, and a documented process for contributing: https://github.com/kubernetes/charts/blob/master/CONTRIBUTING.md

Currently there is a community contributed version, with both gitlab-ce and gitlab-ee flavors. We have an open discussion with the community and here about path forward for those, but we should submit our own PR to the repo with the name we would request which is simply gitlab.