Add new flag to allow CA as text argument for kubelet client

[csauoss]

What this PR does / why we need it:

• This PR adds support for new flag --kubelet-certificate-authority-text to allow passing CA as text for kubelet client. Added corresponding unit tests and updated docs.
• Also corrected the flag name in an existing test case

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #1256

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: csauoss
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[k8s-ci-robot]

Hi @csauoss. Thanks for your PR.

I'm waiting for a kubernetes-sigs 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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[dgrisonnet]

/assign
/triage accepted
/ok-to-test

[csauoss]

@dgrisonnet I do not quite understand the check that failed here as part of build. Is there anything I need to setup? Thanks!

[dgrisonnet]

It sounds like an unrelated error.

/retest

[csauoss]

@dgrisonnet thanks for retesting it. Looks like its all good. can you please review and approve it when you get a chance?
thanks!