ModelInfo for extensions with non-primitive elements

[brynrhodes]

When an extension definition has elements with non-primitive types, the target mapping does not include a ".value" path to access the value of the element within the extension.

This was reported as a CQL issue here:
cqframework/clinical_quality_language#1138

That issue was addressed by manually updating the target mapping, but the tooling should be fixed to address the issue generally.

[ddieppois]

There is an issue building the model info at the moment with the cqf-tooling. I've discussed this issue with @JPercival and it's due to a library that is now outdated. We've checked their repo online and it's seems to be abandoned at the moment. We would need to either remove the tool that rely on this library or ask the team to update their jar (unlikely) from JP.
We can discuss this anytime @brynrhodes