Broaden signature of eigen and eigvals to AbstractMatrix to allow for Adjoint and Transpose input. (#31117)
* Broaden signature of eigen and eigvals to AbstractMatrix to allow
for Adjoint and Transpose input.
Fixes #28714
* Update stdlib/LinearAlgebra/test/eigen.jl
Co-Authored-By: andreasnoack <andreas@noack.dk>
* Update stdlib/LinearAlgebra/test/eigen.jl
Co-Authored-By: Nick Robinson <npr251@gmail.com>