Enable mounting cloud storage in users-sessions

Renkulab supports mounting cloud storage in users-sessions. To enable the feature you need to set the following values in your values-file.yaml:

notebooks:
  cloudstorage:
    s3:
      enabled: true
      installDatashim: true

The installDatashim option will deploy the Datashim <https://datashim-io.github.io/datashim/> Helm chart in the same namespace as the Renkulab chart.