Write particle states as separate lines in track VTK files.

[pshriwise]

… the whole track

Description

This PR modifies track to VTK writing such that particle states are written as separate vtkPolyLine's.

Below are track representations from #3622 before and after this change.

Fixes #3625

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)