make Kubelet bootstrap certificate signal aware

[answer1991]

What type of PR is this?

/kind bug

What this PR does / why we need it:

When I work on #92727, I found Kubelet is not signal aware when bootstrapping certificate. Which means we can only use twice signal to kill Kubelet(through os.Exit(1)) when the certificate bootstrap is in progress. However, when kube-controller-manager or connection to kube-apiserver has some problem, the progress of certificate bootstrap may take a little long time.

Which issue(s) this PR fixes:

None

Special notes for your reviewer:

Add a new function SetupSignalContext which is similar to SetupSignalHandler, but returned is context.Context. context.Context is more standard than stop chan(<-chan struct{}) as a parameter to call an async or long-term function, and I found same new function receive context.Context rather than <-chan struct{}. It's easy to get <-chan struct{} from context.Context(use Context.Done()), but it's not easy to build context.Context from <-chan struct{}(may cost an new goroutine).

Does this PR introduce a user-facing change?:

make Kubelet bootstrap certificate signal aware

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[k8s-ci-robot]

Hi @answer1991. Thanks for your PR.

I'm waiting for a kubernetes 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.

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[answer1991]

/sig node
/ok-to-test
/assign @liggitt

[k8s-ci-robot]

@answer1991: Cannot trigger testing until a trusted user reviews the PR and leaves an /ok-to-test message.

In response to this:

/sig node
/ok-to-test
/assign @liggitt

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[alejandrox1]

@answer1991 you have to be an org member to apply an "ok-to-test" label
/ok-to-test

[answer1991]

@alejandrox1 thanks

[answer1991]

/retest

[answer1991]

/retest

[liggitt]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: answer1991, liggitt

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• cmd/kubelet/OWNERS [liggitt]
• pkg/kubelet/certificate/OWNERS [liggitt]
• staging/src/k8s.io/apiserver/OWNERS [liggitt]

Approvers can indicate their approval by writing /approve in a comment
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[answer1991]

/test pull-kubernetes-conformance-kind-ga-only-parallel

[fedebongio]

Thank you Jordan for taking a look!