Resolve "New helm upstream chart"
General MR
Summary
Adding kptfile and testing against new helm upstream repo: https://github.com/mattermost/mattermost-helm/tree/master/charts/mattermost-operator
Relevant logs/screenshots
(Include any relevant logs/screenshots)
Linked Issue
Upgrade Notices
Added kptfile upgrading functionality with new helm upstream: https://github.com/mattermost/mattermost-helm/tree/master/charts/mattermost-operator