Rearrange kubelet networking codes

[MrHohn]

What this PR does / why we need it:
kubelet package contains multiple *network.go files, also some of the networking related codes scatter in different places. This PR rearranges the networking codes into kubelet_network.go. There is no functional changes.

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 #55451

Special notes for your reviewer:

Release note:

NONE

[MrHohn]

cc @bowei

[tallclair]

/lgtm

[MrHohn]

Rebased, could someone re-LGTM? Thanks. @tallclair @bowei

[bowei]

/lgtm

[k8s-github-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: bowei, MrHohn, tallclair

No associated issue. Update pull-request body to add a reference to an issue, or get approval with /approve no-issue

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[k8s-github-robot]

/test all [submit-queue is verifying that this PR is safe to merge]

[k8s-ci-robot]

@MrHohn: The following tests failed, say /retest to rerun them all:

Test name	Commit	Details	Rerun command
pull-kubernetes-bazel-test	5915b87	link	/test pull-kubernetes-bazel-test
pull-kubernetes-bazel-build	5915b87	link	/test pull-kubernetes-bazel-build
pull-kubernetes-e2e-gce	5915b87	link	/test pull-kubernetes-e2e-gce
pull-kubernetes-node-e2e	5915b87	link	/test pull-kubernetes-node-e2e
pull-kubernetes-e2e-gce-device-plugin-gpu	5915b87	link	/test pull-kubernetes-e2e-gce-device-plugin-gpu

Full PR test history. Your PR dashboard. Please help us cut down on flakes by linking to an open issue when you hit one in your PR.

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[k8s-github-robot]

Automatic merge from submit-queue (batch tested with PRs 55265, 54092, 55353, 53733, 55385). If you want to cherry-pick this change to another branch, please follow the instructions here.