Support inline scripts in postgres chart

[felipecrs]

Like the bitnami one, so that we don't need to create a configmap by ourselves and therefore delete it manually as well after chart uninstallation.

• https://github.com/bitnami/charts/blob/99ea23d43bfe872aa05d682f492b23379c96425e/bitnami/postgresql/values.yaml#L327
• https://github.com/bitnami/charts/blob/master/bitnami/postgresql/templates/primary/initialization-configmap.yaml#L14

[groundhog2k]

See PR. I think this is the feature you are looking for. Please try it out and and give me feedback. I will then merge it.