Unit tests for interop tests

[stefanadranca]

Motivation:

We need unit tests that run the interop tests with the in process transport.

Modifications:

Created a test target and implemented the tests for each interop test, that catch AssertionFailure errors when the interop tests fail.

Result:

We will run the interop tests with the in process transport.

TODO: The CustomMetadata test fails - I will add the metadata handling in the TestService in a different PR