New logging system for the python backend

[RunDevelopment]

We need a new logging system for the backend. As Joey pointed out before, all logging for the backend is actually done by the frontend, so if anything happens to the frontend, we lose all backend logs.

Joey suggested having one log file for the host process and one log file for the worker process, but I'm not sure whether this is the best approach. Having many different log files will make it more difficult to see how logged event across processes correlate with each other. Yes, we can manually order them by time, but that only has a 1s precision.

We also recently had a bug that was caused by an incorrect usage of sanic (#2679, #2738), so need not only a better way to transport log message, but also a logger with a better API.