feat(core): implement 3D grid generation

[imrn99]

Description

Scope: core

Type of change: feat

Content description: TODO

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 54 lines in your changes missing coverage. Please review.

Project coverage is 84.62%. Comparing base (6e38028) to head (25062fc).

Files with missing lines	Patch %	Lines
honeycomb-core/src/cmap/builder/grid.rs	0.00%	54 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #256      +/-   ##
==========================================
- Coverage   85.14%   84.62%   -0.52%     
==========================================
  Files          62       62              
  Lines        8924     8978      +54     
==========================================
  Hits         7598     7598              
- Misses       1326     1380      +54     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[imrn99]

TODO:

• add vertex insertion
• add another drawing of the expected IDs?
• wire the routines to the builder
• tests