Move snapshot APIs and client to v1 (no controller changes)

[xing-yang]

What type of PR is this?
/kind api-change

What this PR does / why we need it:
This PR moves snapshot APIs and client to v1. This only includes API and client changes.
Controller changes are in a separate PR.

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

Move Snapshot APIs to V1.

[xing-yang]

/assign @msau42

[xing-yang]

Hi @yuxiangqian,
Michelle suggested that I submit one PR including only API and clientset changes so we can pass CI. After that submit another PR with controller changes.

Here is the PR including only API and clientset changes (same as #389 except that it does not have controller changes). Please take a look. Thanks.

[xing-yang]

/assign @yuxiangqian

[yuxiangqian]

overall lgtm with some nits. It's really hard to review this type of changes :). I'd highly suggest, if there is next time, to only include those files which are not auto-generated in the first PR (even though the build/test might fail) to ease the process.

[xing-yang]

@yuxiangqian addressed your comments. PTAL.

[xing-yang]

/assign @saad-ali

[yuxiangqian]

/lgtm
/hold
for @saad-ali

[xing-yang]

@saad-ali addressed your comments. Can you please take another look? Thanks.

[saad-ali]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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[xing-yang]

@saad-ali has given lgtm and approved this PR. Removing the hold.

/hold cancel