Refactor Diffraction Module for Nanobind Integration

[mariaward10]

Description

Completed work on diffraction module code for conversion to nanobind

How Has This Been Tested?

Original tests were left unmodified, and the new code passes these tests

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds or improves functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation improvement (updates to user guides, docstrings, or developer docs)

Checklist:

• I have read the CONTRIBUTING document.
• My code follows the code style of this project.
• I have updated the documentation (if relevant).
• I have added tests that cover my changes (if relevant).
• All new and existing tests passed.
• I have updated the credits.
• I have updated the Changelog.

[joaander]

Thanks!