[frontend] Impossible to properly download the binary file of a submission

[precondition]

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Describe the bug

When selecting a submission, INGInious adds a button that lets the user download the submitted file through URL query parameters ?submissionid=XXX&questionid=YYY (from what I gathered).

This correctly opens the file-save dialog window when downloading a source code file like .py or .java.

However, in the case of binary file format such as .xslx, it opens a new tab filled with garbled text like "PK8�5U_rels/.rels���N�0��{�*�5�@���LH�!4�$n���ă�". Copy-pasting the content or saving the page with Ctrl+S don't work — I'm guessing because unprintable binary characters are missing.

INGInious installation details

• Version: v.0.8.2
• Containers version (if applicable) [e.g. the git hash]

To Reproduce Steps to reproduce the behavior:

1. Go to https://inginious.info.ucl.ac.be/course/pae/SINF2MS
2. Submit a .xlsx file
3. Click on the submission
4. Click on the "Save submission file" blue button

Expected behavior The save-file dialog box should open, offering you where to save the binary file.

Screenshots N/A

Desktop (please complete the following information):

• OS: Xubuntu
• Browser : Firefox
• Version : 104

Additional context Add any other context about the problem here.