Add validate_catalogs method for validating single JSON or all JSONs in a directory

[matthew-li]

Changes

• Added a validate_catalogs method that validates a single JSON file, or all JSONs in a directory, returning a list of JSON files and whether they are valid, including any warning and error messages.
  • By default, no more than 10 JSONs are sent to the API within a single request, but this may be configured via a batch_size parameter. (No limit has been set on the API side.)
• Added tests.

How to Test

• Review the code changes and add comments as needed.
• Manual Testing
  • Get an API key and experiment with single catalogs and directories of catalogs.