✨(settings) disable file upload by default & max count

Add FILE_UPLOAD_ENABLED setting (default to False, to avoid
a breaking change). Also adds a max_count_by_user sub setting
to restrict the number of uploaded files per user.

src/backend/core/api/permissions.py

@@ -1,5 +1,6 @@
 """Permission handlers for the Meet core app."""
 
+from django.conf import settings
 from django.http import Http404
 
 from rest_framework import permissions
@@ -116,6 +117,13 @@ class FilePermission(IsAuthenticated):
     Handling soft deletions specificities
     """
 
+    def has_permission(self, request, view):
+        """Allow access only to authenticated users."""
+        if not settings.FILE_UPLOAD_ENABLED:
+            raise Http404
+
+        return super().has_permission(request, view)
+
     def has_object_permission(self, request, view, obj):
         """
         Return a 404 on deleted files or if the user is not the owner