Feature [port-ocean]: Bring your own secret for API credentials

[talpa-robin]

Hey,

I wanted to install port-ocean for the AWS integration. Unfortunately I have to add the Port credentials in plain text into the values.yaml. That's a no go, as we use ArgoCD for deployment and we can't / won't commit sensitive information to our Git.

It would be nice if you would provide a way where one could bring their own secret from which the deployment could extract the API credentials.