feat: add extra envFrom config
This MR improves the ability to add extra environments from a Secret or ConfigMap. We already have the ability to use K8S_SECRET_* variable from Gitlab CI/CD, but as of right now, we can't inject environment variables from another deployment, or use SealedSecret to properly store environment secrets.
This will also cover the last secrets management use case from GitOps with GitLab: How to tackle secrets management (Manage secrets in Git with a GitOps approach)