bug: Filenames with `#` (hash/number sign/pound sign) and `?` (question mark) not supported

[ptamarit]

Uploading a file with a # in its filename fails, and deleting the file does not work.
It is related to: #982 (Files: broken URL for files with slash)

Steps to reproduce the problem

1. Create the file: $ echo 'test' > prefix#suffix.txt
2. Create a new draft in Zenodo
3. Upload the file
4. The uploaded file appears as failed in the UI and the 3rd network request fails because it only includes the part of the filename before the # character:
   
5. Without reloading the page, clicking on the delete icon spins forever without any network request.
6. Reloading the page, the file appears as "Pending"
7. Clicking on the delete icon removes the file from the UI, but the network request fails because it only includes the part of the filename before the # character:
   

Solution

Since the filename is part of the URL (as opposed to the payload), the # character has a special meaning and should be escaped.
Tested for a support case by percent-encoding the filename, and therefore replacing # and %23 and it fixed the problem.