Refactor and improve ISTL matrix testing infrastructure

Santiago Ospina de los Ríosrequested to merge
cleanup/better-matrix-tests into master

Move generic matrix test functions to a dedicated matrixtest.hh header, centralizing and improving reusability of common matrix interface tests.

Consolidate BCRSMatrix specific tests into bcrsmatrixtest.cc, utilizing the generic utilities.

Enhance the robustness of matrix-vector product and vector space operation tests by adding:

  • Explicit result verification with tolerance checks.
  • Consistency checks for Hermitian products.
  • A dense matrix-vector product reference for scalar matrices.

Introduce tests with complex numbers.

Merge request reports