feat: support mountOptions in DeleteVolume

[andyzhangx]

What type of PR is this?
/kind feature

What this PR does / why we need it:
feat: support mountOptions in DeleteVolume
since DeleteVolumeRequest does not have VolumeCapabilities field, this PR reads mountOptions from secret in DeleteVolume as a workaround.

• create a secret with mountOptions

kubectl create secret generic mount-options --from-literal mountOptions="nfsvers=3"

• define a storage class with csi.storage.k8s.io/provisioner-secret-name and csi.storage.k8s.io/provisioner-secret-namespace setting:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: nfs-csi
provisioner: nfs.csi.k8s.io
parameters:
  server: nfs-server.default.svc.cluster.local
  share: /
  csi.storage.k8s.io/provisioner-secret-name: "mount-options"
  csi.storage.k8s.io/provisioner-secret-namespace: "default"
reclaimPolicy: Delete
volumeBindingMode: Immediate
mountOptions:
  - hard
  - nfsvers=3

Which issue(s) this PR fixes:

Fixes #260

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

feat: support mountOptions in DeleteVolume

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: andyzhangx

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• OWNERS [andyzhangx]

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[coveralls]

Pull Request Test Coverage Report for Build 1647676395

• 11 of 20 (55.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.8%) to 77.331%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkg/nfs/controllerserver.go	5	14	35.71%

Totals
Change from base Build 1645184398:	-0.8%
Covered Lines:	539
Relevant Lines:	697

---

💛 - Coveralls

[huanghantao]

Is there a new docker image to use this patch?

[andyzhangx]

Is there a new docker image to use this patch?

@huanghantao try with following command, v3.1.0 is the latest image with this patch:

helm repo add csi-driver-nfs https://raw.githubusercontent.com/kubernetes-csi/csi-driver-nfs/master/charts
helm repo update
helm install csi-driver-nfs csi-driver-nfs/csi-driver-nfs --namespace kube-system --version v3.1.0 --set image.nfs.pullPolicy=Always

[huanghantao]

Thank you, I can delete the PVC normally now!

[kwenzh]

I've had this problem recently, i am using csi driver for nfs， i can delete the pvc normally now too
thank for your contribution,