Replace raw Content-Disposition header creation with util

[hairmare]

In Django 4.2 there is django.utils.http.content_disposition_header() which can help us ensure that the headers are RFC 6266 compliant.

Previous Code

response["Content-Disposition"] = f"attachment; filename={name}"

New Code

from django.utils.http import content_disposition_header

response["Content-Disposition"] = content_disposition_header(as_attachment=True, filename=name)

I'm not sure if this is the canonical way to call it, but it does add unicode support to the filename and hides some implementation specifics.

I'm not sure if its worth it, so feel free to close this if you don't think it is.

Originally posted by @hairmare in #1072 (comment)