Consider moving `sample_test_files/`, `logs/` out of the `src/` folder

[stanislowskij]

The logging stuff should definitely be moved into the top level test/ folder.

sample_test_files/ needs a new home regardless of where it goes. It's used in some of the stack trace tests, so maybe also in the test/ folder? They contain intentionally incorrect code and produce warnings and red highlighting in IDEs that support syntax checking for Clojure.

Relative paths need to be altered wherever these things are used. Check that the tests pass.