verify: Test that re-exported types auxiliary types are correct

[tcharding]

Given RPC method foobar returning type FooBar with conversion error FooBarError.

Our integration testing strategy verifies that FooBar is re-exported correctly. If FooBar has a field with type FooBarAuxType then we do not currently verify that it is correctly re-exported - i would be nice to come up with a way to prove we got it right. Extremely high chance I made mistakes in this area. Not super likely downstream will notice.

[GideonBature]

One way I am thinking is to also use the explicit type check we are using for the normal types. But it might make the test clumsy. To avoid this, I am thinking of creating another test file to check that all re-exports is done correctly including the Auxiliary types.

Another way I am looking at is to use a custom macro method of assert_field_is_exact_type!, which we can define and then call for each re-exported types having auxiliary types.

[tcharding]

Go for it, happy to review what you come up with.