Feature/automatic release

Fixes #112

Adding a release workflow to push docker images with build and a chart to GH.

This PR has:

[ ] been tested on a real K8S cluster to ensure creation of a brand new Druid cluster works.
[ ] been tested for backward compatibility on a real K*S cluster by applying the changes introduced here on an existing Druid cluster. If there are any backward incompatible changes then they have been noted in the PR description.
[ ] added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
[ ] added documentation for new or modified features or behaviors.

datainfrahq / druid-operator