Coverage collection for Kotlin in Headless mode

[Hello-zoka]

Description

Supporting Kotlin in the headless mode was the main goal of the #366 issue (PR #367). Due to the problems with generating .class files after Kotlin compilation, the coverage collection part was separated as an independent issue.

Problems

It was found that KotlinTestCompiler does not produce class files(if you add a similar check as in JavaTestCompiler, it fails). Such information is required to collect coverage in headless mode.