Random Ray Geometry Debug Mode Fix

[jtramm]

Description

When run in geometry debug mode (openmc -g), the Monte Carlo solver will check for any overlapping cells whenever performing a cross section lookup. As the random ray solver doesn't call this function, no overlap checks are ever performed.

This PR simply adds the same overlapping check logic after each ray tracing step is performed in the random ray solver.

I have tested this fix on a random ray input deck featuring a cell overlap (thanks @shimwell!) and it works as expected.

Checklist

• I have performed a self-review of my own code
• I have run clang-format (version 15) on any C++ source files (if applicable)
• I have followed the style guidelines for Python source files (if applicable)
• I have made corresponding changes to the documentation (if applicable)
• I have added tests that prove my fix is effective or that my feature works (if applicable)

[Copilot]

Pull Request Overview

This PR fixes the random ray solver's geometry debug mode to properly detect overlapping cells. When running OpenMC with the -g flag, the Monte Carlo solver performs overlap checks during cross section lookups, but the random ray solver was not performing these checks since it doesn't call that function.

Key Changes:

• Added overlap checking logic in the random ray solver's event_advance_ray() function
• The check is conditional on the settings::check_overlaps flag, matching the Monte Carlo solver's behavior

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[shimwell]

Thanks John, this looks ideal

[shimwell]

As this is a tiny change I think we can go ahead and merge. Will merge on Monday if there are no objections.

[shimwell]

Many thanks for this improvement