Cherry-pick: Add certwatcher to webhook server

[ggriffiths]

Signed-off-by: Grant Griffiths [email protected]

What type of PR is this?
/kind bug

What this PR does / why we need it:
Cherry-pick of #429

Which issue(s) this PR fixes:
n/a

Special notes for your reviewer:
n/a

Does this PR introduce a user-facing change?:

The validation-webhook server will now watch for changes to --tls-cert-file and --tls-private-key-file and update the server's TLS config accordingly.

[xing-yang]

I think we probably need to backport some release-tools changes. See the following errors:

INFO: Version 1.19.1, installing CRDs and snapshot controller
error: unable to read URL "https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v3.0.2/config/crd/snapshot.storage.k8s.io_volumesnapshotclasses.yaml", server reported 404 Not Found, status code=404
error: unable to read URL "https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v3.0.2/config/crd/snapshot.storage.k8s.io_volumesnapshots.yaml", server reported 404 Not Found, status code=404
error: unable to read URL "https://raw.githubusercontent.com/kubernetes-csi/external-snapshotter/v3.0.2/config/crd/snapshot.storage.k8s.io_volumesnapshotcontents.yaml", server reported 404 Not Found, status code=404
error: the server doesn't have a resource type "volumesnapshotclasses"
22:57:31 waiting for snapshot CRDs, attempt #0
error: the server doesn't have a resource type "volumesnapshotclasses"
22:57:33 waiting for snapshot CRDs, attempt #1
error: the server doesn't have a resource type "volumesnapshotclasses"
22:57:35 waiting for snapshot CRDs, attempt #2

[xing-yang]

I think we need these two:

#430
#426

[ggriffiths]

Opened separate PR with updated release tools @xing-yang
#436

[ggriffiths]

/assign @xing-yang

[xing-yang]

This should be a "/kind bug". Also need a release note.

[ggriffiths]

/kind bug

[xing-yang]

release note?

[xing-yang]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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