Feature: Allow to mount custom volume for data

[illmouse]

Description of the change

Right now helm chart only allows mounting datadir as subPath of nextcloud-main PVC. We can see this in deployment template:
{{- if and .Values.persistence.nextcloudData.enabled .Values.persistence.enabled }} - name: nextcloud-data mountPath: {{ .Values.nextcloud.datadir }} subPath: {{ ternary "data" (printf "%s/data" .Values.persistence.nextcloudData.subPath) (empty .Values.persistence.nextcloudData.subPath) }} {{- else }} - name: nextcloud-main mountPath: {{ .Values.nextcloud.datadir }} subPath: {{ ternary "data" (printf "%s/data" .Values.persistence.subPath) (empty .Values.persistence.subPath) }} {{- end }}

My problem is that my data is stored under hostPath (4Tb volume). Moving it to PVC is problematic because CSI driver has a different underlying storage.

Suggestion - allow mounting datadir from one of extraVolumes.

Benefits

Adds more flexibility to the chart by adding another storage management option.

Possible drawbacks

Maybe add a little more complexity in values but seems that chart structure is already complex enough so that wont affect it much.

Additional information

Thanks in advance for considering change :)

[wrenix]

Is it duplicated of #757 (comment)

Do you like to write a PR? For Code or Dokumentation?

[wenbenz]

RE: #757 is there any reason not to codify a pv of type local and, if enabled, associate it to the pvc? If not, I can make a PR.