Allow usage of alternative credentials for Blob storage access

[bnubald]

Current implementation works if the user deploying icenet-etl has Owner or RBAC level access, if it doesn't the icenet-geoapi-processing will fail in processing the uploaded netCDF file from the Blob storage and saving it into the file-system (it just creates a zero-byte file).

With Contributor level access, for the deployment to work, it requires one of the following:

• Service Principal with at least "Storage Blob Data Reader" read-only access permission.
• Managed Identity with same access level as above.
• SAS Token with Read/List level access.
  • Another link