WIP: Rust powered TriGrid

[tmillenaar]

TODO:

• [x] All BaseGrid functions
• [x] Unit-tests for these functions
• [ ] "flat" and "pointy" -> Rethink approach with respect to general rotation
• [x] Docstrings
• [x] Examples using TriGrids
• [x] Release workflow, see https://www.maturin.rs/distribution#github-actions

TODO follow-up MR:

• BoundedTriGrid

[codecov[bot]]

Codecov Report

Attention: 6 lines in your changes are missing coverage. Please review.

Comparison is base (710eeb2) 94.83% compared to head (73236a9) 96.01%.

Files	Patch %	Lines
gridkit/tri_grid.py	95.50%	4 Missing :warning:
gridkit/base_grid.py	84.61%	2 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #50 +/- ## ========================================== + Coverage 94.83% 96.01% +1.18% ========================================== Files 36 39 +3 Lines 2747 3034 +287 ========================================== + Hits 2605 2913 +308 + Misses 142 121 -21 ```

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