SDSS takes specobj_fields but does not query SpecObj

In the SDSS core class, methods like _query_crossid_async()_ take _specobj_fields_ as an input which consequentially breaks the function as it only searches _PhotObj_ table. _field_names.py_ has default retrieval quantities that include _specobj_ and are read into _sdss.core_ but they too break these methods.

The _query_crossid_async()_ should be finished to utilize the _specobj_fields_ input by calling _specobj_ as it does with _photoobj_fields_ and _PhotObj_.

_specobj_ is necessary to retrieve redshift values for objects.

Start in the SDSS core class at _query_crossid_async(), then read _field_names.py to understand the default specobj retrieval quantities. Trace how _photoobj_fields_ is passed to PhotObj and determine where specobj_fields should be handled. Done means queries requesting SpecObj fields, including redshift, return them while existing PhotObj queries continue to work.

Written by the indexing model from the issue text.