Prepare for launch

[dector]

@exercism/kotlin-test-runner Here is basic implementation of auto-test runner. There are some things I'm gonna improve, but you are welcomed to check the code and share your thoughts.

I'll add high-level docs later, there are some kdocs and I tried to make code quite simple.

PR: #4 if you prefer to check changes as a Pull Request.

P.S. Let's use JUnit5 in new exercises! :)

TODO:

• [x] Dockerfile
• [ ] (!) Add docs
• [ ] Decrease docker image size
• [ ] (!) Add more tests
• [ ] (!) Find a way to capture user's in
• [ ] Use Gradle Tooling API
• [ ] Use Path instead of File to run tests on in-memory FS (e.g. jimfs)
• [ ] Try graal / jlink / kotlin native to improve performance and size

[ccare]

Use Path instead of File to run tests on in-memory FS (e.g. jimfs)

If you do implement this, you may want a way of switching it on/off. We're limiting the memory available to the test-runner invocation, so this may tip you over the edge of that limit. On the other hand, the feature might be a huge performance benefit. I'm happy to help you some experiments with it on/off when you get to that point.

[dector]

@ccare jimfs is for testing (running tests for this repo :D) purposes. I guess it's better to use tmpfs if we actually want to allocate some files in memory. :)

[ccare]

ah cool - gotcha. No that makes perfect sense, we can sort out that at an infrastructure level if needs be. Writing test-runners means the phrase 'running tests' is massively overloaded!