Support existing secrets

[larsrnielsen]

I would like avoid storing my username/password in values.yaml and reuse an existing secret for my Artifactory server. An an example of a selfHosted configuration:

 - name: something
   url: something
   # username
   # password
   # token
   secretRef: something

My use case is that I use external-secrets for integration with AWS Secrets Manager and to avoid storing clear text passwords in GitHub.

[davidcollom]

I agree, and think this would be a great addition!