This generalizes the necessary regularization for the umfpacktest and
makes it usable for other algorithms. A hint in Cholmodtest is added and
the other tests using this methods are kept unchanged.

The method was also cleaned up and modernized.

Co-authored-by: Santiago Ospina De Los Ríos <sospinar@gmail.com>

See https://reuse.software/ for a description.

Replace many `Hybrid::ifElse(IsNumber<...` constructions by
using `Impl::asMatrix()`. In some cases the (now only) implementation
of the matrix branch was additionally cleaned up using range-based
for.

[[Imported from SVN: r1609]]

* update configure and Makefiles

[[Imported from SVN: r1100]]

[[Imported from SVN: r1031]]

[[Imported from SVN: r941]]

[[Imported from SVN: r888]]

[[Imported from SVN: r820]]

[[Imported from SVN: r787]]

[[Imported from SVN: r402]]