Feat/existing secret

[agmimidi]

What

This pull request adds an extra field in the values.yaml controllerInfo.existingSecret which can be set as true or false. It then wraps around the creation of the cluster-agent-secret secret. If set as true, then the secret template will not be processed and a secret will not be created.

Why

The current solution for using an existing secret does not work well with ArgoCD, as the lookup feature is not supported by Argo.

How

Bypassing the lookup using the new field, solves the issue without affecting existing functionality.

[juliusmh]

Would be interested in this as well. What about calling it disableSecret or skipSecret?

Our current workaround is to use ESO (external secrets operator) to override the secret created by the helm release.