Add functionality to refine a TreeMesh using an "image"

[jcapriot]

Adds a refinement function that accepts an ndarray input the same shape as the underlying base mesh of the tree mesh. It will recursively refine the cells if that cell contains more than a single unique value.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.85%. Comparing base (cfc9f2e) to head (0e7dde7).
⚠️ Report is 6 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #406      +/-   ##
==========================================
+ Coverage   86.81%   86.85%   +0.03%     
==========================================
  Files          91       91              
  Lines       18802    18856      +54     
  Branches     2119     2123       +4     
==========================================
+ Hits        16323    16377      +54     
  Misses       1801     1801              
  Partials      678      678              

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