✨ Kotlin sample source file with multiple classes

[LVMVRQUXL]

📝 Description

Having a single class in sample files being a current limitation for Kotools Samples, we want to support Kotlin sample source files with multiple classes.

import kotlin.test.Test
import kotlin.test.assertEquals

class IntKotlinSample {
    @Test
    fun plus() { // Extracted in 'build/kotools-samples/extracted/IntKotlinSample/plus.md'.
        val x = 1
        val y = 2
        val result: Int = x + y
        assertEquals(3, result)
    }
}

class LongKotlinSample {
    @Test
    fun plus() { // Extracted in 'build/kotools-samples/extracted/LongKotlinSample/plus.md'.
        val x = 1L
        val y = 2L
        val result: Long = x + y
        assertEquals(3, result)
    }
}

By doing so, we don't need to check if sample source files contain a single class.

[LVMVRQUXL]

Resolved in #42.