Unittests

[glrs]

This pull request includes significant updates to the test suite for the core and module utilities, like YggdrasilUtilities and ConfigLoader classes. The changes primarily focus on enhancing test coverage, improving test reliability, and ensuring proper handling of various edge cases.

Enhancements to YggdrasilUtilities tests:

• Added setup and teardown methods to TestYggdrasilUtilities to manage temporary configuration directories and reset module cache.
• Improved test coverage by adding new test cases for handling ImportError, AttributeError, and file existence checks in YggdrasilUtilities.load_realm_class and YggdrasilUtilities.load_module.
• Added tests for environment variable handling, including cases where variables do not exist or have default values.
• Introduced tests for sequence file operations, including reading, writing, and handling errors.

Enhancements to ConfigLoader tests:

• Added initialization and configuration loading tests, including handling of invalid JSON, file not found, and unexpected exceptions.
• Improved test coverage for the __getitem__ method, ensuring proper behavior for existing and non-existing keys, and immutability of the configuration data.
• Added tests for the config_manager instance and module-level configuration loading.
• Included tests to ensure safe handling of directory traversal in file paths.

Similar for the rest.