⚡️(backend) remove content from Document serializer when asked

The frontend can fetch the retrieve endpoint just for having the title.
Everytime, the content is added and to get the content, a request is
made to the s3 bucket. A query string `without_content` can be used, if
the value is `true` then the content is not added (and not also not
fetch).

src/backend/core/api/serializers.py

@@ -225,8 +225,16 @@ class DocumentSerializer(ListDocumentSerializer):
         fields = super().get_fields()
 
         request = self.context.get("request")
-        if request and request.method == "POST":
-            fields["id"].read_only = False
+        if request:
+            if request.method == "POST":
+                fields["id"].read_only = False
+            if (
+                serializers.BooleanField().to_internal_value(
+                    request.query_params.get("without_content", False)
+                )
+                is True
+            ):
+                del fields["content"]
 
         return fields