CustomArgParser doesn't support the yaml_file_arg_key functionality

[shatu]

I believe the intention of providing a yaml_file_arg_key argument to the CustomArgParser is that the end-user can choose the command-line name for providing their config file. However, currently, the value provided to yaml_file_arg_key is not utilized and the config param name is just assumed to be config_path while fetching and parsing the config in Line 83.

PyMarlin/pymarlin/utils/config_parser/custom_arg_parser.py

Line 83 in 11bce75

self._parse_config(args.config_path)