Move external facing podresources apis to staging

[RenaudWasTaken]

What type of PR is this?
/kind api-change
/area code-organization
/sig node

What this PR does / why we need it:
podresources API is external facing. Currently we are forcing folks to import them from k8s.io/kubernetes which is not optimal. We should instead make them available from the k8s.io/kubelet repo to make it easier for them.

Which issue(s) this PR fixes: N/A

Special notes for your reviewer:
Note, for people who will be broken by this change (i.e: people pulling from kubernetes master), they can either:
a) Freeze the kubernetes version they rely on, which they already should, in the go.mod they should have something along the lines of

require (
        ...
	k8s.io/kubernetes v0.17.4
        ....
)

b) Change the import path:

sed -i 's#k8s.io/kubernetes/pkg/kubelet/apis/podresources/v1alpha1#k8s.io/kubelet/pkg/apis/podresources/v1alpha1#g" *.go
go mod tidy

/cc @dashpole @derekwaynecarr

Enhancement issue: kubernetes/enhancements#606
Current Kep: https://github.com/kubernetes/enhancements/blob/master/keps/sig-node/compute-device-assignment.md
Updated Kep: kubernetes/enhancements#1865

Note: Change is targeting current milestone and we expect to introduce v1 in the next release.
Also note that despite the API name, it is currently in beta (since 1.15).

Does this PR introduce a user-facing change?:

external facing API podresources is now available under k8s.io/kubelet/pkg/apis/

[RenaudWasTaken]

/assign @dims

Note that I followed the model of your PR: #83551

[fejta-bot]

This PR may require API review.

If so, when the changes are ready, complete the pre-review checklist and request an API review.

Status of requested reviews is tracked in the API Review project.

[RenaudWasTaken]

/label api-review

[SergeyKanzhelev]

/assign @dashpole

[SergeyKanzhelev]

/retest

[dashpole]

/lgtm
/approve

Thanks @RenaudWasTaken

[dashpole]

/priority important-soon

[neolit123]

please see this PR merge policy change.
https://groups.google.com/g/kubernetes-dev/c/YXGBa6pxLzo

the milestone should be applied later in the cycle.
for Q you can ask in #sig-release.

thanks
/milestone clear

[RenaudWasTaken]

I'll probably wait a bit that regular maintenance restarts before rebasing this PR :) !
It's not critical to stability and doesn't fix any tests.

[SergeyKanzhelev]

I'll probably wait a bit that regular maintenance restarts before rebasing this PR :) !
It's not critical to stability and doesn't fix any tests.

@RenaudWasTaken this time came =) It's now in 1.20 milestone

[RenaudWasTaken]

Will take care of it this week then!

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dashpole, liggitt, RenaudWasTaken

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Needs approval from an approver in each of these files:

• hack/OWNERS [liggitt]
• pkg/kubelet/OWNERS [dashpole,liggitt]
• staging/src/k8s.io/kubelet/OWNERS [dashpole,liggitt]
• test/e2e_node/OWNERS [dashpole,liggitt]
• vendor/OWNERS [liggitt]

Approvers can indicate their approval by writing /approve in a comment
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[RenaudWasTaken]

/retest

[dashpole]

/lgtm