Support Application CRD in K8s charms

[Kenneth Koski]

The Application CRD provides a way to declare metadata about a deployed application in Kubernetes:

https://github.com/kubernetes-sigs/application

An example of an Application custom resource can be found here:

https://github.com/kubernetes-sigs/application/blob/master/docs/examples/wordpress/application.yaml

The existence of this CRD is relied upon for some behavior in the Kubeflow bundle, such as the Central Dashboard knowing which version it is, see here for that logic:

https://github.com/kubeflow/kubeflow/blob/master/components/centraldashboard/app/k8s_service.ts#L156

Could we get support in Juju for automatically creating these? Although they can be created with the `customResources` section of the pod spec, that would require a lot of manual code that seems like something Juju should handle itself. In particular, it seems like a lot of the metadata in an Application could be directly ported over from what's in metadata.yaml.

[Canonical Juju QA Bot (juju-qa-bot)]

This bug has not been updated in 2 years, so we're marking it Low importance. If you believe this is incorrect, please update the importance.