The initial stub at adding support for cAdvisor

[ichekrygin]

This PR adds the initial support for metrics collected from the Kubelet's advisor sub-service, with the initial support for Network metrics only.

[linux-foundation-easycla[bot]]

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[k8s-ci-robot]

Hi @ichekrygin. 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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[pwittrock]

/ok-to-test

[linux-foundation-easycla[bot]]

• :white_check_mark: login: ichekrygin / name: Illya Chekrygin (9c94f82af9061f18618ae95b092da5241abab89d, 3ea8777bf320934ccfc1587931f6b7e5b51b5e37)
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[ichekrygin]

/ok-to-test

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/kubernetes-sigs/usage-metrics-collector/blob/main/OWNERS)~~ [campoy] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[campoy]

/lgtm