Propose to add addtional test problem from QPLIB

[LiuZhexuan]

Prof. Mittelmann have addtional convex QP test problem for commercial QP solvers, see https://plato.asu.edu/ftp/cconvex.html. Most of these problem are not too huge for open source solvers to solve. It would be great if these can be added, Thanks!

[stephane-caron]

Thanks for pointing out this test set 👍

Adding problems to the benchmark is too low on my stack to be able to start working on it right now, but if a contributor is interested in extending the benchmark with these additional problems, PRs are welcome and I would be happy to help with reviewing and merging.