Scaling methods

[sshin23]

There are a few options for implementing scaling
cc: @amontoison @frapac

• Scaling the factorized block at the linear solver level
• Scaling the full KKT system at the MadNLPSolver level

Since mature CPU solvers have built in scaling method, the default behavior should be a dummy scaler, doing nothing. For less reliable linear solvers, scaling methods can be applied.