feat: first version of helm chart

[thschue]

This PR

• Adds the first version of a helm chart
• Adds simple workflow to release the chart

[kosmoz]

Generally the chart works great! 🎉

I did find some issues though, which we should address.

Also, the CRDs are currently auto-generated and placed in the deploy directory by a gradle task. We should probably do something similar for the chart, however I think it's okay if that's done in a follow-up ticket.

[thschue]

Thank you for your review! I addressed the comments, I'd propose that we do the auto-generation of CRDs in a second issue.

[kosmoz]

I tried the chart again and it works now. 🎉

If you could implement the following changes, we would be ready to merge this PR:

• After some discussion, we decided that we would prefer to rename the values identifier glasskubeOperator to operator.
• Some time has passed since this PR was created (this is our bad…), so it is necessary to add the missing CRDs and update the RBAC manifest.
• We decided to keep the dependencies as part of the chart, but they should be disabled by default. This means that for each dependency there should be a condition in the Chart.yaml and its default value in values.yaml should be set to false.
• The appVersion can be updated to 0.5.2.
• The MariaDB Operator version can be updated to 0.15.1, which the latest version of our operator should be compatible with.