Adding Support For Existing PVC

[paimonsoror]

Added support for existing PVC's. This is a more up to date version of a lot of the enhancements made in the following PR, but recreated for a more fresh PR #19 .

Note:

This is a breaking change as the data and attachment objects have been moved under a storage key.

[guerzon]

Hello @paimonsoror, thanks for the PR. Here are a few thing that have to be adjusted as well as a result of putting data and attachment under the new storage key:

1. charts/vaultwarden/templates/configmap.yaml lines 37, 38, 40, and 41.
2. charts/vaultwarden/templates/_pvcSpec.tpl lines 2, 4, and 27.
3. charts/vaultwarden/templates/_helpers.tpl line 88.
4. charts/vaultwarden/templates/deployment.yaml lines 43 - 49 should then look like this (to avoid a dangling 2nd volumes: key in the template spec):

         {{- range $pvc := (fromYaml (include "vaultwarden.pvcSpec" .)).volumeClaimTemplates }}
         volumes:
           {{- $newName := printf "%s-%s-0" $pvc.metadata.name $.Release.Name }}
           - name: {{ $pvc.metadata.name }}
             persistentVolumeClaim:
               claimName: {{ $newName }}
         {{- end }}
   

[guerzon]

LGTM