✨(backend) add subrequest auth view for collaboration server

We need to improve security on the access to The collaboration server
We can use the same pattern as for media files leveraging the nginx
subrequest feature.

src/backend/core/tests/documents/test_api_documents_retrieve.py

@@ -26,6 +26,7 @@ def test_api_documents_retrieve_anonymous_public():
             "ai_transform": document.link_role == "editor",
             "ai_translate": document.link_role == "editor",
             "attachment_upload": document.link_role == "editor",
+            "collaboration_auth": True,
             "destroy": False,
             # Anonymous user can't favorite a document even with read access
             "favorite": False,
@@ -89,6 +90,7 @@ def test_api_documents_retrieve_authenticated_unrelated_public_or_authenticated(
             "ai_transform": document.link_role == "editor",
             "ai_translate": document.link_role == "editor",
             "attachment_upload": document.link_role == "editor",
+            "collaboration_auth": True,
             "destroy": False,
             "favorite": True,
             "invite_owner": False,