Hessians with blending for SUPG

Ponsuganth Ilangovan Ponkumar Ilangorequested to merge
ponsuganth/second-derivatives into main

This adds,

  • Second derivatives (Hessians) of shape functions
  • Affine and blending transformation for the Hessians
  • Hessian of the blending map, directly calculated with sp.diff in GeometryMap
  • Uses the blending substitution optimization from !3 (merged) for hessians of the blending map
  • A test is also added under hyteg_integration_tests but as there were no previous forms to compare, a simple hand calculated math integration value is hard coded to compare

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