Add support for generic ephemeral storage

[justusbunsi]

Is your feature request related to a problem? Please describe

jenkinsci/kubernetes-plugin#1489 introduces the possibility to use ephemeral storage volumes in the Build pod specification. According to

helm-charts/charts/jenkins/templates/_helpers.tpl

Lines 480 to 492 in 762105a

	{{- if (eq .Values.agent.workspaceVolume.type "DynamicPVC") }}
	dynamicPVC:
	{{- else if (eq .Values.agent.workspaceVolume.type "EmptyDir") }}
	emptyDirWorkspaceVolume:
	{{- else if (eq .Values.agent.workspaceVolume.type "HostPath") }}
	hostPathWorkspaceVolume:
	{{- else if (eq .Values.agent.workspaceVolume.type "Nfs") }}
	nfsWorkspaceVolume:
	{{- else if (eq .Values.agent.workspaceVolume.type "PVC") }}
	persistentVolumeClaimWorkspaceVolume:
	{{- else }}
	{{ .Values.agent.workspaceVolume.type }}:
	{{- end }}

the Helm Chart currently not support that new type genericEphemeralVolume.

Describe the solution you'd like

I happily provide a PR to add that support. What I would need to know is whether I should also bump the kubernetes-plugin in such PR to the supporting version or if I should split it into different PRs? It looks like there is no automatism right now to update the listed plugins.

Describe alternatives you've considered

No response

Additional context

No response

[timja]

I happily provide a PR to add that support. What I would need to know is whether I should also bump the kubernetes-plugin in such PR to the supporting version or if I should split it into different PRs? It looks like there is no automatism right now to update the listed plugins.

Combined PR is fine, there's discussion in this pull request about automating the update of the plugin: #979