Add a filesys.FileSystem interface to kio.LocalPackageReader

[campoy]

This PR adds a new FileSystem field to LocalPackageReader to improve its testability.

Updates #3873

[k8s-ci-robot]

@campoy: This PR has multiple commits, and the default merge method is: merge.
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[k8s-ci-robot]

Hi @campoy. 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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[natasha41575]

/ok-to-test

[monopole]

/lgtm

very nice, thanks!

[KnVerey]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: campoy, KnVerey

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