Add data validation at startup to help reduce errors when making API constraint changes

[calvinmclean]

Description

Since I am not using a database or DB migrations, whenever I change my data structures to add a new "required" field, my existing test data might not have these fields. This will cause a lot of errors that should not exist if new data was created through the API. I should have the application validate at startup and fail to run (make optional/forceable with config/CLI arg) if current data doesn't fit API constraints.