Logger error when filename is not specified even when the logger is turned off

[Naphann]

Describe the bug

When the logger is turned off via setting in the .ini file as shown below

**.logger.enabled_log = false

The logger initialization still shows error when run with CmdEnv if the parameter **.logger.log_filename is not set.

<!> Error: The simulation attempted to prompt for user input, set cmdenv-interactive=true to allow it: "Enter parameter 'two_node_MIM.logger.log_filename' (unassigned):" -- in module (quisp::modules::Logger::LoggerModule) two_node_MIM.logger (id=3), during network setup

Expected Behaviour

It should not ask or expect the filename parameter when logger is turned off.

suggested fix

add default filename as empty string "" and when the logger is turned on. It should expect a valid filename.