Adds Struct logs with .gz file rotation

• Add logs in json format with fields - utc_timestamp, message, logger, level, class_name, method_name, file_name, line_number
• A log file name should end with ".log" (example: "ga4gh-testbed-infrastructure.log"). If a log file name is provided in the config, then the JSON logs will be written to a log file, which will be .gz rotated every day at UTC. For now, we are saving a 30-day history of logfiles.
• If a log file name is not provided, it defaults to console logging, which is also in JSON format and has the same fields as mentioned above.
• removed the methods trace, warn, debug, etc from TestbedLoggingUtil class so that the true caller line number, method, class, and filename are captured in the logs.

@jb-adams Please let me know if you have any questions.