Headless mode Kotlin

[Hello-zoka]

Added Kotlin support and method-level generation in the headless mode. Coverage collection has to be implemented in a separate PR(see #379)

Closes #337, #366

Progress:

• Kotlin test generation and compilation support
• Method-level generation support

[Vladislav0Art]

I marked it as "in progress" because the "Kotlin coverage collection" task in the description is not ticked.

[Hello-zoka]

I marked it as "in progress."

I was sure that we'd discussed releasing Kotlin headless without coverage support since it requires some work to understand why Kotlin class files don't appear at all after compilation, which is required for such a task and probably will take a lot of efforts

So, this PR is marked ready for review again, but it doesn't close #366. I've modified it's description to show the current status and problems

[Vladislav0Art]

I marked it as "in progress."

I was sure that we'd discussed releasing Kotlin headless without coverage support since it requires some work to understand why Kotlin class files don't appear at all after compilation, which is required for such a task and probably will take a lot of efforts

So, this PR is marked ready for review again, but it doesn't close #366. I've modified it's description to show the current status and problems

@Hello-zoka
Do you mean that we want to merge this PR without the coverage for Kotlin (in the upcoming release, I assume)? In this case, I recommend creating a separate issue just for coverage and linking these two issues together (mentioning one in the other as a continuation).