Implemented clear for material

[MicahGale]

Pull Request Checklist for MontePy

Description

This implements clear for Material.

Fixes #665, fixes #667, fixes #666.

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General Checklist

• I have performed a self-review of my own code.
• [d] The code follows the standards outlined in the development documentation.
• I have formatted my code with black version 25.
• I have added tests that prove my fix is effective or that my feature works (if applicable).

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Documentation Checklist

• I have documented all added classes and methods.

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Additional Notes for Reviewers

Ensure that:

• The submitted code is consistent with the merge checklist outlined here.
• The PR covers all relevant aspects according to the development guidelines.
• 100% coverage of the patch is achieved, or justification for a variance is given.

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📚 Documentation preview 📚: https://montepy--668.org.readthedocs.build/en/668/