[9.x] Add configurable timezone support for WorkCommand output timestamps

[trm42]

Introduces a new configuration option queue.log_timezone, so that the php artisan queue:work command can output the timestamps in a different timezone than the in application default app.timezone.

The rationale for this addition is that this is already doable for log files made through Log facade with Log::setTimezone but the WorkCommand is not using the Logging subsystem but Console\OutputStyle to write directly back to the stdout and stderr.

When we're pushing the logs from the php artisan queue:work to a logging service like AWS Cloudwatch, it expects the timestamps to be in UTC but the previously used application default timezone can be something else leading to discrepancy between Log::'ed log files and console command output. In this specific case Cloudwatch isn't too happy about timestamps happening in the future.

The configuration has been added as optional. If it has not been defined, the code uses the current application timezone.