Improve bindings for configuration types

[wdeconinck]

This pull request refactors and extends the Python bindings for configuration objects in atlas4py, improving maintainability and usability. The main changes involve extracting the configuration binding logic into a new dedicated source file, enhancing the Python interface for configuration objects, and updating tests to cover the new features.

Refactoring and modularization:

• Extracted all logic related to Python bindings for configuration objects (eckit::Configuration, eckit::LocalConfiguration, atlas::util::Config) into new files: _atlas4py_Config.cpp and _atlas4py_Config.hppThis significantly improves code organization and maintainability.

Enhancements to Python bindings:

• Replaced previous custom Python conversion and binding code for configuration objects with a more robust and feature-rich implementation in the new module. The new bindings provide a consistent interface for getting, setting, and representing configuration objects, and add static constructors for creating Config objects from keyword arguments, YAML strings, and files.
• Updated the __repr__ methods for several types (Projection, Domain, Grid, Spacing, Metadata) to use the new atlas4py::make_object function for consistent and improved string representations.

Testing improvements:

• Added new tests to tests/test_bindings.py to verify the new Config constructors (from_kwargs, from_yaml, from_file) and their correct behavior, including nested configuration and type handling.

[Copilot]

Pull request overview

This PR refactors the atlas4py Python bindings for configuration-related types by extracting config binding logic into a dedicated module and expanding the Python-facing Config API (including YAML/file constructors), while updating string representations to use the new config-to-Python conversion helper.

Changes:

• Split configuration binding/conversion logic into _atlas4py_Config.{hpp,cpp} and register it from _atlas4py.cpp.
• Expanded Python bindings for eckit::Configuration / eckit::LocalConfiguration / atlas::util::Config (mapping protocol, constructors from kwargs/YAML/file).
• Added pytest coverage for new Config behaviors and bumped the package dev version.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
tests/test_bindings.py	Adds tests for new Config constructors and mapping/contains semantics.
src/atlas4py/CMakeLists.txt	Ensures the new config binding translation unit is compiled into _atlas4py.
src/atlas4py/_atlas4py.cpp	Wires in bind_Config() and updates several __repr__ paths to use make_object().
src/atlas4py/_atlas4py_Config.hpp	Declares the new config binding/conversion API surface used by _atlas4py.cpp.
src/atlas4py/_atlas4py_Config.cpp	Implements the new binding/conversion logic and Config constructors.
pyproject.toml	Bumps atlas4py version from 0.41.1.dev4 to 0.41.1.dev5.

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[wdeconinck]

Hi @tehrengruber this is the following PR in line, now ready for you to review :)