API integration tests

[gavv]

We should add at least one integration test in Java that creates a sender, a receiver, transfers samples, and checks that they were transferred correctly.

Such an integration test for the C API can be found here: https://github.com/roc-streaming/roc-toolkit/blob/master/src/tests/public_api/test_sender_receiver.cpp

We can go further and add a few more tests, similar to tests described roc-streaming/roc-toolkit#328. I don't think we need to replicate all of them, but it'd be nice to test at least some of the key features.

See also roc-streaming/roc-go#29 for more hints.