Test the new instance-based OMEdit API with the entire testsuite

[casella]

As the implementation of #8425 nears the end, we should test this new functionality extensively to make sure it doesn't break.

Beyond manual testing, it would be nice to have a CI job that runs through the whole library testsuite, mocking the API calls it would receive from OMEdit and making sure the NF doesn't fail on them. If it does, the model should be reported for further investigation.

This test would dramatically increase the quality of implementation, without waiting for distressed users to point out that they can't see any diagram, which is what happens today if the new infrastructure fails.