[TECH] Support structured logging

[pilosus]

Define a technical problem.
Plain text logs are fine for local development, but are not suitable for production use.
Structured logs in the form of JSON events stream considered one of the best practices for logging.

Describe possible solution.
Basic JSON-based logging config file for logback logging. Users may use it as a reference to write their own configs or just use right away. Docs update is needed.