Add external-storage tests for nfs

[Madhu-1]

We have external-storage tests for cephfs https://github.com/ceph/ceph-csi/tree/devel/scripts/k8s-storage not for nfs, This is a tracker for nfs tests

### Tasks
- [ ] add `driver-nfs.yaml` in `scripts/k8s-storage` directory
- [ ] add `sc-nfs.yaml.in` in `scripts/k8s-storage` directory
- [ ] verify the output of a manual trigger CI run that NFS tests are executed

[github-actions[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed in a week if no further activity occurs. Thank you for your contributions.

[AryanSwaroop]

Can this issue be assigned to me if no one is working on it !!

[nixpanic]

Can this issue be assigned to me if no one is working on it !!

Sure! Thank you for having a go at it.

[AryanSwaroop]

Sure, I'll try my best to resolve this !

[AtulBoyal]

Hi, I’d love to work on this issue as my first contribution. Is it still available? If so, I’d like to start working on it!