feat: support pv/pvc metadata in subDir parameter

[andyzhangx]

What type of PR is this?
/kind feature

What this PR does / why we need it:
feat: support pv/pvc metadata in subDir parameter

• subDir parameter supports following pv/pvc metadata transform

if subDir value contains following strings, it would be converted into corresponding pv/pvc name or namespace

• ${pvc.metadata.name}
• ${pvc.metadata.namespace}
• ${pv.metadata.name}

Which issue(s) this PR fixes:

Fixes #502

Requirements:

• uses conventional commit messages
• includes documentation
• adds unit tests
• tested upgrade from previous version

Special notes for your reviewer:

Release note:

feat: support pv/pvc metadata in subDir parameter

[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 2523760258

• 27 of 33 (81.82%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.5%) to 77.411%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pkg/nfs/controllerserver.go	13	16	81.25%
pkg/nfs/nodeserver.go	8	11	72.73%

Totals
Change from base Build 2490727659:	0.5%
Covered Lines:	610
Relevant Lines:	788

---

💛 - Coveralls

[jingxu97]

/assign @gnufied @jsafrane

[andyzhangx]

/assign @gnufied @jsafrane

@gnufied @jsafrane there is discussion here about the requirement, this nfs driver should have quite similar requirement as smb driver: kubernetes-csi/csi-driver-smb#503 (comment)

[jsafrane]

/lgtm