♻️(backend) rename, factorize and improve the subrequest media auth view

We want to use the same pattern for the websocket collaboration service
authorization as what we use for media files.

This addition comes in the next commit but doing it efficiently
required factorizing some code with the media auth view.

docker/files/etc/nginx/conf.d/default.conf

@@ -6,7 +6,7 @@ server {
 
     location /media/ {
         # Auth request configuration
-        auth_request /auth;
+        auth_request /media-auth;
         auth_request_set $authHeader $upstream_http_authorization;
         auth_request_set $authDate $upstream_http_x_amz_date;
         auth_request_set $authContentSha256 $upstream_http_x_amz_content_sha256;
@@ -21,8 +21,8 @@ server {
         proxy_set_header Host minio:9000;
     }
 
-    location /auth {
-        proxy_pass http://app-dev:8000/api/v1.0/documents/retrieve-auth/;
+    location /media-auth {
+        proxy_pass http://app-dev:8000/api/v1.0/documents/media-auth/;
         proxy_set_header Host $host;
         proxy_set_header X-Real-IP $remote_addr;
         proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;