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)