Multus configuration add namespace isolation

[Sispheor]

What type of PR is this? /kind feature

What this PR does / why we need it:

Add the support of network isolation configuration in Multus.

Which issue(s) this PR fixes: Fixes #11594

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

NONE

Add the support of network isolation configuration in Multus.

[k8s-ci-robot]

Hi @Sispheor. Thanks for your PR.

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[tico88612]

/ok-to-test

[yankay]

Thanks @Sispheor /approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: cyclinder, Sispheor, tico88612, yankay

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