Hide Kotlin coroutines impelementation details in the trace

[eupp]

Consider the following example:

val executorService = Executors.newFixedThreadPool(2)
executorService.asCoroutineDispatcher().use { dispatcher ->
    val job = launch(dispatcher) {
            counter++
    }
    job.join()

Currently, if a lincheck test fails in such a case, it would also output in the trace all the implementation details of the coroutines.

We need to improve on this, and do not show these details by default to the user.

Partially depends on #501 and #506

[ndkoval]

Please also see #303