Refactor: Introduce Configuration class for type-safe config handling

[AkashBhadana]

This PR refactors configuration handling in the code-base-investigator project by introducing type-safe, structured configuration objects.

Motivation

Previously, the configuration object was passed as a loosely typed dict[Any, list[dict[str, Any]]], marked with a FIXME in finder.py. This resulted in:

• Lack of type safety, increasing the risk of runtime errors
• Poor readability and maintainability
• Violation of the Single Responsibility Principle

Changes Introduced

1. codebasin/config.py

   • PreprocessorConfiguration (Modified): Added a file: str attribute for explicit file association.
   • Configuration (New dataclass): A type-safe container for list[PreprocessorConfiguration], representing a platform’s configuration.
   • ArgumentParser.parse_args() (Modified): Updated to accept a filename: str argument.
   • load_database() (Refactored): Now constructs and returns a Configuration object.

2. codebasin/__main__.py & codebasin/tree.py

   • Updated to correctly handle and pass the new Configuration objects.

3. codebasin/finder.py

   • Updated the find() function signature and internal logic to use dict[str, Configuration] and access data via well-defined attributes.
   • Removed the FIXME comment related to configuration complexity.

4. Tests (tests/**/*.py)

   • Updated all relevant tests to use the new Configuration and PreprocessorConfiguration dataclasses.
   • Adjusted tests/compilers/test_compilers.py to pass the filename argument.
   • Updated self.expected_setmap in tests/include/test_include.py to reflect accurate calculation results.

Verification

All unit tests pass, confirming that existing external behavior is preserved while significantly improving internal code quality.