KEP-4671: Add Workload API

[macsko]

What type of PR is this?

/kind feature

What this PR does / why we need it:

This PR adds a Workload API based on KEP-4671. Moreover, it adds a WorkloadReference to the Pod spec.

This PR doesn't contain the gang scheduling implementation that is posted in #134722.

Which issue(s) this PR is related to:

Part of #134471
Fixes #134472
Fixes #134473
Fixes #134474
Fixes #134478

KEP: kubernetes/enhancements#4671

Special notes for your reviewer:

Does this PR introduce a user-facing change?

Introduce scheduling.k8s.io/v1alpha1 Workload API to allow for expressing workload-level scheduling requirements and let kube-scheduler act on those.

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

- [KEP]: https://github.com/kubernetes/enhancements/tree/master/keps/sig-scheduling/4671-gang-scheduling

[k8s-ci-robot]

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[k8s-ci-robot]

LGTM label has been added.

Details

Git tree hash: cbce30a3aa15b504deb8b5b319c9641309378cb8

[dom4ha]

/lgtm

[k8s-ci-robot]

LGTM label has been added.

Details

Git tree hash: d6f4b6c5437819f682404c26403942f4c1f97dcf

[k8s-ci-robot]

@macsko: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-kubernetes-apidiff-client-go	54b6ab6	link	false	/test pull-kubernetes-apidiff-client-go
pull-kubernetes-e2e-kind-alpha-beta-features	54b6ab6	link	false	/test pull-kubernetes-e2e-kind-alpha-beta-features

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.

Details

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes-sigs/prow repository. I understand the commands that are listed here.