Update Rakefile to publish Helm chart
Adds support files needed to be able to deploy the GitLab Helm chart from release-tools.
This is being done to support issue gitlab-org/charts/gitlab#1442 (closed), moving the Helm chart release process to look more like omnibus and CNG.
- Related MR in charts: gitlab-org/charts/gitlab!1641 (merged)
Edited by Dustin Collins