DM-45764: Return ingest_date as astropy time from general query

[andy-slac]

There is no easy way to catch/convert ingest_date in the rows returned
from all queries. For now only the general query can return ingest_date,
so it is an easy fix for that case, though it requires checking type
of the value in that column for each row.

Checklist

• ran Jenkins
• added a release note for user-visible changes to doc/changes
• (if changing dimensions.yaml) make a copy of dimensions.yaml in configs/old_dimensions

[codecov]

Codecov Report

Attention: Patch coverage is 97.05882% with 1 line in your changes missing coverage. Please review.

Project coverage is 89.57%. Comparing base (d09db1e) to head (6366d3b).
Report is 3 commits behind head on main.

Files	Patch %	Lines
...tler/direct_query_driver/_result_page_converter.py	91.66%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1060      +/-   ##
==========================================
+ Coverage   89.55%   89.57%   +0.02%     
==========================================
  Files         357      357              
  Lines       46173    46190      +17     
  Branches     9486     9487       +1     
==========================================
+ Hits        41349    41374      +25     
+ Misses       3488     3484       -4     
+ Partials     1336     1332       -4     

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