Expose TreeMesh geometric intersections used for refine functions.

[jcapriot]

This PR unifies (and exposes) the geometric intersection tests used by the refine functionalities. The goal is to allow the user to see which cells actually intersected those geometric objects and use them to search for things.

This will expose operations to find cells that intersect with a

• Line (updated and fixes get_cells_along_line method not robust for tree mesh #346 )
• Box (updated)
• Ball
• Triangle
• Vertical Triangular Prism
• Tetrahedron
• Plane (which is a new addition to address MemoryError using mesh.plot_slice() with a TreeMesh of around 500,000 cells #355.)

It makes use of C++ templates and classes to reduce the repeated code for each of the different geometric objects.

[codecov]

Codecov Report

Attention: Patch coverage is 94.54545% with 24 lines in your changes missing coverage. Please review.

Project coverage is 86.06%. Comparing base (c394964) to head (d1caf10).
Report is 23 commits behind head on main.

Files with missing lines	Patch %	Lines
discretize/mixins/mesh_io.py	52.00%	5 Missing and 7 partials ⚠️
discretize/tests.py	88.52%	3 Missing and 4 partials ⚠️
tests/base/test_volume_avg.py	97.50%	1 Missing and 1 partial ⚠️
discretize/tree_mesh.py	50.00%	1 Missing ⚠️
tests/tree/test_intersections.py	99.29%	0 Missing and 1 partial ⚠️
tests/tree/test_tree_io.py	97.72%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #356      +/-   ##
==========================================
- Coverage   86.29%   86.06%   -0.23%     
==========================================
  Files          89       90       +1     
  Lines       18726    18478     -248     
  Branches     2961     2968       +7     
==========================================
- Hits        16159    15904     -255     
- Misses       1881     1882       +1     
- Partials      686      692       +6     

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