add MNASolverGPUMagma: a sparse CUDA solver using the magma library.
also changes a bit of the gitlab pipeline. For now the changes using the new magma library fail in the CI as cricket does not support CUDA kernels in .so yet. But MNASolverGPUMagma works and I want to avoid tedious rebasing in the future, so I set the stage allowed to fail.
Signed-off-by: Niklas Eiling email@example.com