Add short names for Volume Snapshot CRDs

[robbie-demuth]

NOTE: This is a backport of #604

What type of PR is this?

/kind feature

What this PR does / why we need it:

This allows end users to run kubectl get vs, for example, instead of
kubectl get volumesnapshot. The following short names have been
implemented:

• VolumeSnapshot - vs
• VolumeSnapshotContent - vsc, vscs
• VolumeSnapshotClass - vsclass, vsclasses

Which issue(s) this PR fixes:

Fixes #603

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

Yes

Cherry-pick: #604: Added short names for Volume Snapshot CRDs:
* VolumeSnapshot - vs
* VolumeSnapshotContent - vsc, vscs
* VolumeSnapshotClass` - vsclass, vsclasses

[k8s-ci-robot]

Hi @robbie-demuth. Thanks for your PR.

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[xing-yang]

Can you add "Cherry-pick: #604: " in the beginning of the release note?

[robbie-demuth]

Done!

[xing-yang]

/ok-to-test

[xing-yang]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: robbie-demuth, xing-yang

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