Add logging options to Helm chart

[Baarsgaard]

Expose available logging options in the Helm chart.
Useful for people who use structured logging solutions.
I found #1659 and thought it would be a quick fix.

I also found some securityContext options that were not replicated to/from the kustomize configuration, those were aligned along with the logging args.

Replication steps:

# Prepare kind cluster
export KUBECONFIG=~/.kube/kind-grafana-operator
make kind-start

# Install Helm chart with no modifications
helm upgrade -i grafana-operator ./deploy/helm/grafana-operator --version v5.13.0

# Verify default configurations
kubectl get deployments.apps grafana-operator -o yaml | grep -A 10 containers:
# Verify standard/default log output
kubectl logs deployments/grafana-operator

# Install helm chart with overwritten logging values
helm upgrade -i grafana-operator ./deploy/helm/grafana-operator --version v5.13.0 \
  --set logging.encoder=json --set logging.level=debug --set logging.time=rfc3339

# Verify arg changes in deployment
kubectl get deployments.apps grafana-operator -o yaml | grep -A 10 containers:
# Verify level, encoding, and time format have changed in the logs
kubectl logs deployments/grafana-operator