Add comprehensive test suite for the argument_parser module including:
- Tests for _convert_to_bool with truthy/falsy values
- Tests for _convert_to_list with JSON and comma-separated inputs
- Tests for _convert_to_dict with valid/invalid JSON
- Tests for convert_string_to_type with various type annotations
- Tests for convert_arguments with typed functions
- Tests for ArgumentConversionError exception class
This establishes the foundation for the project's test infrastructure
with pytest configuration already in place.
