Migrate CRD generation to Python dataclasses

The Dask operator has a number of Custom Resource Definitions. Many of these definitions have specs from other resources nested within them. For example the `scheduler` and `worker` parameters within `DaskCluster` have nested `PodSpec` specifications because these will ultimately be created as Pods by the controller.

https://github.com/dask/dask-kubernetes/blob/734d001836fad228cca809093feec3d07cd634a6/dask_kubernetes/operator/customresources/templates.yaml#L36

To generate the Custom Resource Definitions that we ship in the [Dask Kubernetes Operator Helm Chart](http://helm.dask.org/#dask-kubernetes-operator) we have a [whole pile of yaml](https://github.com/dask/dask-kubernetes/tree/main/dask_kubernetes/operator/customresources) that contains the definition templates. Then we have a [`pre-commit` hook](https://github.com/dask/dask-kubernetes/blob/734d001836fad228cca809093feec3d07cd634a6/ci/pre-commit-crd.py) that runs [`k8s-crd-resolver`](https://github.com/elemental-lf/k8s-crd-resolver) which renders the templates into the [helm chart crds directory](https://github.com/dask/dask-kubernetes/tree/main/dask_kubernetes/operator/deployment/helm/dask-kubernetes-operator/crds).

I'm conscious that `k8s-crd-resolver` appears to be unmaintained and has not had new schema definitions introduced since Kubernetes `1.25` which went EOL in October 2023. I also opened https://github.com/elemental-lf/k8s-crd-resolver/issues/6 over a year ago which has not had any response.

It could be interesting to explore migrating the CRD generation to Python Dataclasses instead of YAML templates. There is a library that can do this called [`kubecrd`](https://github.com/maxking/kubecrd) but this also appears to be unmaintained. It also does not support having multiple version schemas and so would stop us from impementing #753.

As a response to this I'm exploring generating Custom Resource Definition objects in `kr8s` from dataclasses (https://github.com/kr8s-org/kr8s/issues/456). Putting this code in `kr8s` will help ensure it is tested and maintained. It would also allow you to create multiple dataclasses, one for each version of the schema.