Integration test of API version requirements

[rawlinp]

We need a set of integration tests that test and verify the client-API version contract so that existing clients are not broken by things like the addition of new required fields in existing APIs.

The tests would have the client make PUT/POST requests with only the required fields of that API (i.e. either omitting optional fields from the request JSON altogether and/or explicitly passing the optional fields with null values). The tests should always expect 200s with no errors from these requests and will fail if the API contract is broken -- for example, if a new required field has been added to the API.

[mitchell852]

reviewed in 7/13/2021 working group. leaving as is.