title: Use URI on expo Document-picker to get the file itself
body: <p>I got suck while trying to upload a file from react-native (android using expo) to a back-end server.
  I got from <code>DocumentPicker.getDocumentAsync()</code> this response </p>
  
  <pre><code>    {
        "name": "QuitusInscription_30769_59.pdf",
        "size": 41438,
        "type": "success",
        "uri": "file:///data/user/0/host.exp.exponent/cache/ExperienceData/%2540anonymous%252Fcsdl_frontend-46ddf63e-90ab-44b3-a4c7-6ad7aad5cccc/DocumentPicker/a40a6599-4900-439a-9e9b-57fa555a80c9.pdf",
      }
  </code></pre>
  
  <p>My problem is now how to use the uri in order to get the file itself ? so that I could send it to the back-end server</p>
  
  <p>Thanks</p>