Draft: Add a view to raw vector data with `DenseVector` interface
Summary
This MR introduces a span DenseVectorSpan
over a consecutive sequence of values with a given number. This span has an interface like a DenseVector
and can be used in all the places where a DenseVector
is expected, e.g. in DenseMatrix::solve
. This allows to wrap nonDune types like std::vector
in the Dune interface. It also would allow to replace the ScalarVectorView
since a single scalar value is just a sequence of length 1.
Requirements

This MR is based on !1334 (merged)
Note
A similar span can be easily introduced for matrices. A generalization is already implemented for "tensors" in https://gitlab.duneproject.org/simon.praetorius/dunetensor//blob/main/dune/tensor/tensorspan.hh?ref_type=heads
Edited by Simon Praetorius