👔(backend) display css and code in template endpoint

We would like to duplicate a template from the frontend.
For that we need to access the css and code of the template.
So we add the css and code to the template endpoint.

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

@@ -133,7 +133,7 @@ def test_api_documents_retrieve_authenticated_related_direct():
         "id": str(document.id),
         "title": document.title,
         "abilities": document.get_abilities(user),
-        'is_public': document.is_public,
+        "is_public": document.is_public,
     }
 
 
@@ -247,7 +247,7 @@ def test_api_documents_retrieve_authenticated_related_team_members(
         "id": str(document.id),
         "title": document.title,
         "abilities": document.get_abilities(user),
-        'is_public': False,
+        "is_public": False,
     }
 
 
@@ -344,7 +344,7 @@ def test_api_documents_retrieve_authenticated_related_team_administrators(
         "id": str(document.id),
         "title": document.title,
         "abilities": document.get_abilities(user),
-        'is_public': False,
+        "is_public": False,
     }
 
 
@@ -445,5 +445,5 @@ def test_api_documents_retrieve_authenticated_related_team_owners(
         "id": str(document.id),
         "title": document.title,
         "abilities": document.get_abilities(user),
-        'is_public': False,
+        "is_public": False,
     }