[distribute] First draft of distribute wrench

This PR creates an entity called DistributeWrench which obtains the desired contact wrench from the DCM controller and uses it to output a reference ZMP for the CoM admittance controller.

Right now, no optimization problem is computed. The desired wrench is equally split in two between left and right, but these values are not employed (the foot admittance control is needed for that). This is just a sketch, but it is already partially functional. Previously, the ZMP computed by the admittance controller was employed directly, bypassing the wrench computation.

Not really happy of the vertical component, but it is working in simulation, we can be deal with it later.

This adds the dependency of eigen-quadprog.