Treat first actor (operation) as regular method call

[eupp]

On the following test

class RecursiveSpinLockRepeatsOperationTest {
    private val value = AtomicBoolean(false)

    fun foo() {
        if (value.get()) return
        foo()
    }

    @Test
    fun test() = ModelCheckingOptions()
        .iterations(0)
        .addCustomScenario { parallel { thread { actor(::foo) } } }
        .checkImpl(this::class.java)
        .checkLincheckOutput("spin_lock/recursive_spin_lock_repeats_operation.txt")
}

Lincheck produces an incorrect spin-lock

The following interleaving leads to the error:
| ------------------------------------------------------------------------------------------------- |
|                                             Thread 1                                              |
| ------------------------------------------------------------------------------------------------- |
|   foo(): <hung>                                                                                   |
|     /* The following events repeat infinitely: */                                                 |
| ┌╶> value.get(): false at RecursiveSpinLockRepeatsOperationTest.foo(RecursiveSpinLockTest.kt:301) |
| └╶╶ switch (reason: active lock detected)                                                         |
| ------------------------------------------------------------------------------------------------- |
All unfinished threads are in deadlock

[eupp]

Draft PR #453

[eupp]

The problem is because in the ManagedStrategy class we treat the top-most function (the actor) not as a regular method call. We should refactor this to prevent this bug and similar bugs.