Migrate disk API group to library model

[alexander-ding]

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespaces from that line:

/kind api-change

/kind bug
/kind cleanup
/kind design
/kind documentation
/kind failing-test
/kind feature
/kind flake

What this PR does / why we need it:
Part of #217 (migrating one API Group to v2's library based model). The v1 model will stick around until all API groups are migrated.

Which issue(s) this PR fixes:

Fixes #234

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

Deferring release note till all API Groups are migrated.

[k8s-ci-robot]

Hi @alexander-ding. Thanks for your PR.

I'm waiting for a kubernetes-csi member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

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[mauriciopoppe]

/ok-to-test

[mauriciopoppe]

I created an issue for it, please add a reference to it

[mauriciopoppe]

I saw that TestDisk is tested in the logs:

=== RUN   TestDisk

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: alexander-ding, mauriciopoppe

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