Support ProxQP OSQP to solve QPIK and TSID QP problems

[traversaro]

It would be interesting to support the ProxQP solver (https://github.com/Simple-Robotics/proxsuite) when solving QP problems created by QPIK and TSID.

This would probably require:

• Abstract existing calls to osqp-eigen under an abstraction layer (let's call it BLFQP)
• Add support in BLFQP for ProxQP, either by directly writing the integration with ProxQP or by interfacing with an existing abstraction layer for QP programs, such as https://github.com/isri-aist/QpSolverCollection or CasADi .

[GiulioRomualdi]

I think having an abstraction layer for the solvers is doable.

[traversaro]

For reference, the abstraction layer used in stack-of-tasks/tsid is https://github.com/stack-of-tasks/tsid/blob/v1.7.0/include/tsid/solvers/solver-HQP-base.hpp .

[traversaro]

Other recent QP solvers that report intersting performances on benchmarks:

• https://github.com/oxfordcontrol/Clarabel.cpp
• https://github.com/PREDICT-EPFL/piqp