Create examples-inspired integTests

[dk1844]

Currently, the code in examples submodule already serves as integration test (sort of), but pursuing other features (separate module/runnable aspirations/... see #99).

But it would be nice to have actual integration tests instead of logically residing in atum (core module) under src/test.

Optional:

• the tests can be distinguished by suffix (-IntegrationSuite perhaps) and we can even a named profile to run them