Add catalog verification pipeline

[delucchi-cmu]

This might look like a report of what's inside the catalog, to be verified against the catalog owner's expectation of the catalog contents.

Useful things to consider:

• total number of sources
• column-level schema (names and types)
• column-level units
• values "close" to original values (identical for integers, "close enough" for floating points)
• distribution of radec among points
• allow for comparisons against some golden file(s)

[nevencaplar]

Connected with #374, #373, and #375