Cyl mesh generalization

[jcapriot]

Generalizes the Cylindrical mesh to not be hard-coded starting at r=0 or having a full azimuthal discretization.

[codecov]

Codecov Report

Merging #321 (7704fc4) into main (0f9fe1f) will increase coverage by 0.28%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #321      +/-   ##
==========================================
+ Coverage   85.41%   85.69%   +0.28%     
==========================================
  Files          38       38              
  Lines       11420    11580     +160     
==========================================
+ Hits         9754     9924     +170     
+ Misses       1666     1656      -10     

Impacted Files	Coverage Δ
discretize/base/base_tensor_mesh.py	88.45% <100.00%> (ø)
discretize/cylindrical_mesh.py	96.54% <100.00%> (+2.32%)	⬆️
discretize/mixins/mpl_mod.py	72.59% <100.00%> (+0.07%)	⬆️
discretize/mixins/vtk_mod.py	88.76% <100.00%> (+0.91%)	⬆️
discretize/tests.py	81.02% <100.00%> (+0.28%)	⬆️

... and 3 files with indirect coverage changes