Refactor impulse control system: relocate integrated_impulse_control to src.impulse

- Moved integrated_impulse_control_clean.py functionality to src/impulse/integrated_impulse_control.py.
- Created src/impulse/__init__.py for package initialization and backward compatibility.
- Updated imports in tests/conftest.py to reflect new module structure.
- Removed deprecated code and streamlined mission planning and execution logic.
- Ensured all classes and functions are accessible via the new impulse package.

Author: arcticoder