Add Type Hints to Core Decorator Functions

[abeltavares]

Description

Enhance the existing core decorator functions (pre_condition, post_condition, and invariant) by adding type hints to their parameters and return types. This will improve code clarity and facilitate static type checking with tools like MyPy.

Suggested Implementation

Add type hints to the parameters and return types of the core decorator functions. Ensure that type hints cover all parameters, including check, exception_type, and message.

Acceptance Criteria

• Type hints are added to all core decorator functions.
• Type hints cover all parameters and return types.
• Unit tests are written to ensure the type hints are correct.