Use dart:developer for console printing

[shilangyu]

Theres a dedicated function in dart:developer for printing log records from package:logging: https://api.flutter.dev/flutter/dart-developer/log.html. This function takes all arguments from logging's LogRecord:

    developer.log(
      rec.message,
      name: rec.loggerName,
      error: rec.error,
      stackTrace: rec.stackTrace,
      level: rec.level.value,
      time: rec.time,
      sequenceNumber: rec.sequenceNumber,
      zone: rec.zone,
    );

I don't exactly know what it does other than printing to console, but the printing is much nicer than current's PlainTextPrintStrategy strategy. Unfortunately strategies don't allow for custom printing, just for custom string creation.