Fetcher: Improve api return types.

This changes following:

• decorator @ztm_api_unwrapper has been renamed to @ztm_api_unwrap_to_list_of_dicts,
• stop sets by name and lines for stop return single list, since we know what we asked for,
• other apis using decorator return list of dicts with asked entries, instead of dict like "key": list of results, and same results share indices across those lists, making it awkward