global clipper

[plusk01]

Implements a semidefinite program solver to solve the resulting semidefinite relaxation from the maximum spectral radius clique (MSRC) problem.

• Uses SCS 3.2.3
• Only relies on third party code if CMake option CLIPPER_ENABLE_SCS is ON (ON by default)
• If solution is rank 1, then we found the global optimum of the MSRC problem
• note that this method is slower than first-order CLIPPER, but faster than if we just gave the MSRC problem to a non-convex solver