inconsistency in URL function/dict.source/named_collections

Function/table engine is url. Dict.source is http/https.

also there inconsistency in supported features

| function url | dict.source http | named_collections |
|:----------:|:-------------:|:------:|
| | `` | |
| | `` | `` |

Compare the URL function/table engine with Dict.source using http/https and the named_collections support listed in the issue. First trace where these three configurations define their supported features, then establish the intended consistent behavior and document or test the resulting alignment.

Written by the indexing model from the issue text.