✨ add support for kubernetes +required annotations

[liggitt]

Fixes #943

Adds support for Kubernetes +required annotations on fields, fixes support for +optional annotations on fields, adds tests.

[JoelSpeed]

/lgtm

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: fcc1db5628bc614c8d0efd02ed32a6bccddf3a9c

[sbueringer]

One minor finding

[sbueringer]

Thx!

/lgtm
/approve

[k8s-ci-robot]

LGTM label has been added.

Git tree hash: 73dd5a5d249c1f73fcfdd9bb272a4536aaceee5f

[k8s-ci-robot]

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[ahmetb]

If anyone has time, it would be good to document this on https://book.kubebuilder.io/reference/markers/crd-validation.

[sbueringer]

Agree. Although it will be only available via a release in August.

Might be good to then go over the controller-tools release notes once kubebuilder bumps and update the docs accordingly
(there was also this PR: #938)

/cc @camilamacedo86

[camilamacedo86]

We need to update the docs, I added the info in : kubernetes-sigs/kubebuilder#3794 (comment)