Finalize JSDC3 dataset

[bourgesl]

The complete JSDC3 dataset contains all data for ASCC stars (2.5e6 rows):

• BRIGHT (sptype)
• FAINT (no sptype)

Major data sources retrieved in 24.07:

• SIMBAD
• ASCC (I/280)
• 2MASS (II/246)
• GAIA DR3 (I/355)
• allWise (II/328)

Remaining actions:

• update SIMBAD information (20e6 rows in late 24.11) in vobs/config/prepare_candidates
• compute stats on properties (generic function) to only save 'not empty' properties in the catalog query cache (vobsSCENARIO)
• adopt the eCSV format for the new catalog query cache (per catalog + final merge), but still support TSV output, in order to manipulate such large CSV tables directly with topcat/stilts and postgres database (psql ?), see https://www.star.bris.ac.uk/~mbt/topcat/sun253/inEcsv.html