OZG-4786 Introduce Unit-test, external config properties and helper

run_helm_test.sh

src/main/helm/Chart.yaml

src/main/helm/templates/_helpers.tpl

src/main/helm/templates/configmap.yaml

src/main/helm/templates/deployment.yaml

src/main/helm/templates/secret.yaml

src/main/helm/templates/service.yaml

src/main/helm/values.yaml

src/test/helm-linter-values.yaml

src/test/helm/configmap-test.yaml

src/test/helm/deployment-test.yaml