Add list of cli parameters or env vars that can be passed into the installed operator helm charts

[soenkeliebau]

We currently have no way of configuring operators that are installed via our helm charts, even though the docs mention parameters: https://docs.stackable.tech/home/stable/hbase/configuration

We should have a list of parameters or env vars that can be set in values.yaml and is then passed through to the operator deployment.

[fhennig]

Additionally we should then document that instead of what we have now, since the env vars and config flags are not useful by themselves.

Besides Helm we might need a similar solution that works on OpenShift.