Add VS namespace to VSC printed columns

[tsmetana]

/kind feature

What this PR does / why we need it:
When using kubectl get volumesnapshotcontent the result prints also referenced VolumeSnapshot object. That is not enough to identify the correct one though, since VolumeSnapshot is namespaced. It would be probably good to display also the namespace of the VolumeSnapshot.

Does this PR introduce a user-facing change?:
Yes.

The namespace of the referenced VolumeSnapshot is printed when printing a VolumeSnapshotContent.

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[k8s-ci-robot]

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[xing-yang]

/ok-to-test

[xing-yang]

@tsmetana, can you show the new results of kubectl get volumesnapshotcontent?

[tsmetana]

The output with the new additional column looks like this:

NAME                                               READYTOUSE   RESTORESIZE   DELETIONPOLICY   DRIVER                  VOLUMESNAPSHOTCLASS   VOLUMESNAPSHOT   VOLUMESNAPSHOTNAMESPACE   AGE
snapcontent-7b12a296-c23e-4e8a-88ee-eacd191470ca   true         1073741824    Delete           pd.csi.storage.gke.io   csi-gce-pd-vsc        mysnap1          default                   5m47s

It would be definitely prettier if we could just display one column with default/mysnap1 but I don't know if that's even possible.

[xing-yang]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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