Mocking creates uncompilable code for Kotlin, due improper `mockedConstruction` type

[tyuldashev]

Description

When user tries to use mocking for external classes UTBot creates var mockedConstruction = null which usage in the code cause type compatibility errors

To Reproduce

Steps to reproduce the behavior:

1. In UTBot settings set Generated test language to Kotlin other leave default
2. Enable Force mocking static methods
3. Generate tests for following code

import java.util.Random

class RandomInt {
    fun multByRandom(x: Int): Int {
        val random: Random = Random();
        return x * random.nextInt();
    }
}

Expected behavior

Compilable code is generated

Actual behavior

Generated test cannot be compiled. See its beginning below.

    @Test
    fun testMultByRandom1() {
        var mockedConstruction = null
        try {
            val mockClassCounter = AtomicInteger()
            mockedConstruction = mockConstruction(Random::class.java) { RandomMock: Random,
                                                                        context: MockedConstruction.Context
             -> when (mockClassCounter.get()) {
                    0 -> {
                        (`when`(RandomMock.nextInt())).thenReturn(0)
                    }
                }
                mockClassCounter.getAndIncrement()
            }

Visual proofs (screenshots, logs, images)