added voxel plot

[shimwell]

WIP

Description

Adding voxel_plot function to region, cell, universe, geometry, model

Fixes # (issue)

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)