Task order uploads and downloads were broken. Uploads were broken
because file content was eing read in as plaintext every time, resulting
in encoding issues. I updated the bundle to use the newer Azure JS SDK.
We can now use a method for uploading browser files directly without
having to read their content. This required a few small internal changes
to the upload component, since the response structure is different.
I also removed the `downloadUrl` method from the JS uploader since it
was not being used.
Downloads were broken because the method that generates the download
link was not updated to use the BlobSasPermissions class from the
updated Azure Python SDK.
