Provide a generic helm chart for deploying operators

[csviri]

Although helm charts are probably at some points are at some point specialized for each project, probably would help the users to prodive a default helm chart as a template, where they can easily use to deploy operator for a generic use case. Supporting feature flags for example for deploying operator with leader election (or without), customizing log levels etc.
Users can then take it and tailor it to their needs.

Additional notes:

• We should test it in an e2e test, so we are sure not breaking it
• Also now unit testing is nicely supported for helm charts so we should add also default helm unit tests
  https://github.com/helm-unittest/helm-unittest

As motivation we could take a look for helm charts like:

• the Flink Operator one: https://github.com/apache/flink-kubernetes-operator/tree/main/helm/flink-kubernetes-operator