Refactor to use Eigen::ConstRef for vertices

[zfergus]

Description

• Remove Vector<T, dim, max_dim> and replace it with either Eigen::Vector<T, dim> or VectorMax<T, max_dim>
• Updated constructors in Edge, Edge2, Edge3, Face, Point2, and Point3 classes to accept Eigen::ConstRefEigen::MatrixXd instead of Eigen::MatrixXd for vertices.
• Renamed GradType to GradientType in edge.hpp, edge3.hpp, and point3.hpp for consistency.
• Adjusted gradient and hessian function signatures in Point2 and Point3 to use Eigen::Vector and VectorMax types.
• Modified utility functions in smooth_collisions_builder to accept Eigen::ConstRef for vertices.

[codecov]

Codecov Report

❌ Patch coverage is 97.19626% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 97.40%. Comparing base (e62964b) to head (c7602cd).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...ipc/smooth_contact/distance/primitive_distance.hpp	82.35%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #200      +/-   ##
==========================================
- Coverage   97.41%   97.40%   -0.01%     
==========================================
  Files         149      149              
  Lines       23746    23748       +2     
  Branches      798      797       -1     
==========================================
+ Hits        23131    23132       +1     
- Misses        615      616       +1     

Flag	Coverage Δ
unittests	97.40% <97.19%> (-0.01%)	⬇️

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