Improve moments radiation

[adamdempsey90]

Background

This does 2 things:

• Add an option to not subcycle the moments radiation. If selected, the radiation calculation will happen during the main integration step. I'm finding that this leads to better behavior in low density regions (the velocity there won't grow).
• Rewrite the matter-coupling step and remove the old ones. Turns out doing this part robustly is hard, so i had 5.6 Sol rewrite it. It added some safety features and fallbacks that are actually being used in the raytracing PPD problem. That pgen no longer has zones that "fail" and the results look better (especially when not subcycling).

The cost of this new approach is definitely more, but I think the robustness might make it worth it.

This change may not play nice with restarts.

Description of Changes

Checklist

• New features are documented
• Tests added for bug fixes and new features
• (@lanl.gov employees) Update copyright on changed files
• Any contribution that was created or modified with the assistance of generative AI must have a comment disclosing this such as // This file was created in part or in whole by generative AI