add media endpoint for XSendfile

backend/files/media_urls.py

@@ -0,0 +1,22 @@
+from django.urls import path
+from rest_framework import status
+from rest_framework.decorators import api_view
+from rest_framework.response import Response
+
+from files.models import File
+
+
+@api_view(['GET'])
+def media_urls(request, id, format=None):
+    try:
+        file = File.objects.get(file=id)
+        return Response(status=status.HTTP_200_OK,
+                        headers={'X-Accel-Redirect': f'/redirect_media/{id}'})  # TODO Expires and Cache-Control
+
+    except File.DoesNotExist:
+        return Response(status=status.HTTP_404_NOT_FOUND)
+
+
+urlpatterns = [
+    path('<path:id>', media_urls),
+]