Our previous OpenAPI schema validator that we implemented ourselves
was useful training wheels for our understanding OpenAPI properly, and
was mostly correct. But given that we've finally reached the point
where our OpenAPI file accurately describes the API, it makes sense to
switch to use an official OpenAPI validator. We lose some ability to
do exclude rules for particular elements, but those were primarily
important for us when we had a lot of them.
As part of this change, we need to add `additionalProperties: false`
for all of our dictonaries/objects where we've documented every
parameter; otherwise the OpenAPI schema checker won't know that we
expect every parameter to be documented.
We had a bug in `validate_against_openapi_schema` that prevented it
from correctly inspecting nested arrays.
Fix the bug and address all the exceptions, either via
EXCLUDE_PROPERTIES or fixing them when simple. Also add a test case
for nested verification.