Support extraVolumes and extraVolumeMounts

[chrisduong]

I have a use case where I inject the K8s secret with Kubernetes Secrets Store CSI Driver.

To be able to do this, I need to have extra Volumes or extra Volume Mounts (optional) for the deployment.

I'll be happy to open the PR if people think it is useful.

[Syntax3rror404]

There is allredy a option to use existing secrets so you can use a secret CSI like vault