Add helm chart option for elasticsearch credentials as a secret

Currently the artifactory chart allows you to specify Postgres connection information by referencing a kubernetes secret. It would be helpful if we could do the same for the elasticsearch instance used by filebeat/insight.

We would like to send artifactory and Xray metrics to an external elasticsearch. Currently, the only way to do that is by hardcoding the URL, username, and password, or making a custom init container to update the system.yaml. If the Xray and Artifactory charts were configured to accept secret names and data keys in the same way you can reference your postgres connection string and master/join keys it would be a great addition to the charts.