Make it Possible to have sparse fill matrices

[MicahGale]

Pull Request Checklist for MontePy

Description

This fixes a bug where sparse fill matrices can't be parsed. The MCNP manual does allow for fill sparsity in the multiple universe fill system at the end. This handles this case by padding the list with effective "jumps", and then defaulting those to universe 0 (per the manual).

At first all the fill universe data was one long list. I was doing a lot of janky things to edit just the middle of the list, etc. I realized though: this is a small grammar. So I actually added a syntax tree that splits this into indices (the 0:1 section for multi-universe), universes, and transform. This greatly simplified the code and increased legibility.

Fixes #601

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• I have performed a self-review of my own code.
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📚 Documentation preview 📚: https://montepy--695.org.readthedocs.build/en/695/

[MicahGale]

This is paused while I figure out how to handle partial matrices.

[MicahGale]

• Add this to the hypothesis tests in tests/test_universe_integration.py

[MicahGale]

Ok this time it is ready @tjlaboss.