Remove dependency on `k8s.io/kubernetes`

[astefanutti]

WHY

k8s.io/kubernetes is not meant to be depended on as explain in kubernetes/kubernetes#79384.

WHAT

This causes issues with some tools.

HOW

Replace the dependency:

https://github.com/project-codeflare/appwrapper/blob/37ce35b914eb89715cf5f8c01e928e3124ac3abc/pkg/utils/utils.go#L30

With the right one from k8s.io/api/core/v1.

[astefanutti]

/cc @dgrove-oss

[dgrove-oss]

I'm pretty sure k8s.io/api/core/v1 isn't enough (that was what I initially tried last week when fixing #131). Just depending on core/v1 doesn't get the "right" AddToScheme function implementation that causes the generated defaulting functions to be registered.

I'll try to figure out some how to get those defaulters without the direct dependency.

[dgrove-oss]

Looks like we can't get the defaulters through one of the published k8s modules so we will have to replicate the needed functionality instead. This will be a bit fragile, but appears to be unavoidable if we can't access the generated functions.

[tardieu]

Could we run defaulter-gen ourselves?

[astefanutti]

It's annoying but not blocking, so we can leave it as if we think there isn't any "good" solution.

Ideally these defaulters would be published as part of https://github.com/kubernetes/api.

[dgrove-oss]

In the short term, I'm going to copy in the generated defaulter (and associated helpers) I'm using into our utils package as package-private functions. That will let us clean the dependency. Longer term, I'd like to kick off a discussion with the Kueue maintainers about whether they really need to use such a picky and fragile notion of equality.

[astefanutti]

Sounds good, thanks.