Ensure that the OSQP report as status output not the return value of solveProblem(), but the output of solveProblem()

[DavideBarbone]

As per title this PR contains the fix for the solver status of the Simulink OSQP block.

[traversaro]

Technically speaking this is a change of behavior, but it actually permits to have a meaningful signal coming out of the status output, so I guess it is a fair change. I will nevertheless bump the minor version instead of the patch in the new wb-toolbox release to make that clear.

To provide more detail on the change: before this PR, the status output of the OSQP block returned the return value of solveProblem, see https://github.com/robotology/osqp-eigen/blob/v0.8.1/include/OsqpEigen/Solver.hpp#L123 . This method returned the OsqpEigen::ErrorExitFlag, that however returns OSPQ errors (see https://github.com/robotology/osqp-eigen/blob/b9ce7391350e0f1c71e49f7574a8785fb617b5e6/include/OsqpEigen/Constants.hpp#L43-L57), and not the solver exit status, that is instead contained in https://github.com/robotology/osqp-eigen/blob/b9ce7391350e0f1c71e49f7574a8785fb617b5e6/include/OsqpEigen/Constants.hpp#L23-L38 and returned by getStatus, see https://github.com/robotology/osqp-eigen/blob/b9ce7391350e0f1c71e49f7574a8785fb617b5e6/include/OsqpEigen/Solver.hpp#L173 . So this PR changes the logic to ensure that status return the output of getStatus.

fyi @mfussi66 @Gio-DS

[traversaro]

Probably I merged this a bit in a rush, anyhow @gabrielenava you may want to have a look to this change.