Add more detailed catalog validation

[delucchi-cmu]

Feature request

These should be optional, as some kind of strict validation.

• Compare the pixels in _metadata with partition_info.csv
• Compare the pixels in leaf parquet files with partition_info.csv
• Check that catalog can be loaded as a valid parquet dataset
• Print some statistics as you run:
  • number of partitions
  • number of rows
  • approximate on-sky coverage (in sq degrees, and in % coverage)

Before submitting
Please check the following:

• I have described the purpose of the suggested change, specifying what I need the enhancement to accomplish, i.e. what problem it solves.
• I have included any relevant links, screenshots, environment information, and data relevant to implementing the requested feature, as well as pseudocode for how I want to access the new functionality.
• If I have ideas for how the new feature could be implemented, I have provided explanations and/or pseudocode and/or task lists for the steps.