[ENHANCEMENT] authentitcate to external elasticsearch using an API key

[hamza-m-masood]

Describe the use case:

Currently, it is required to supply a username and password in the values.yaml in order to connect to an external elasticsearch.
The managed elasticsearch instance on google cloud generates an API key that is not possible to use on our values.yaml when connecting to an external elasticsearch instance.

Describe the enhancement/feature:

Desired outcome and acceptance tests:

[aabouzaid]

There is a WIP related to this feature on the apps side. We need to check if it's supported in the apps before we can support it in the Helm chart.

[jessesimpson36]

@theburi do you know of a feature request from the application-side that provides this functionality?