Implement case-scoped `System.out` capture

[dector]

For now JUnit is capturing output on testsuit level.

Should be implement debug() function as an easy option instead?

[dector]

Current idea is to use custom Test Reporter that will be attached to JUnit Platform and will capture required data for each test. Unfortunately, JUnit5 is distributed on with legacy JUnit4 reporter that doesn't support per-test stdout capture.