Get the URL and Sas needed to upload an attachment to cloud storage.

To use with the Azure Storage SDK or the Microsoft Blob Service REST API (https://docs.microsoft.com/en-us/rest/api/storageservices/put-blob).
If you choose to work with the former, you will need both the 'AttachmentUrl' and 'AttachmentSas' values and you can disregard the 'BlobServiceRestApiUrl' value.
If you choose to work with the latter, you must upload your document using HTTP PUT using the URL in 'BlobServiceRestApiUrl' and you can
disregard the 'AttachmentUrl' and 'AttachmentSas' values.
For improved user experience, the following headers should be used when uploading the file:

• Content-Type: The MIME content type of the blob. For example, for a PDF, "application/pdf" should be used.
• x-ms-blob-content-disposition: The content-disposition of the blob. We recommend using "filename=YourFileName.extension".
  Note that Basic Authentication is required for all requests as such, make sure to provide the Authorization header with a valid value.