Velocity controller preparation for jumping

[CarlottaSartore]

This PR introduces the following changes for implementing the jumping:

• Introduction of a constraint for the torso z velocity;
• Introduction of activation function for torso velocity;
• Introduction of activation function for holonomic constraint;
• Angular Momentum as a constraint.

C.C. @VenusPasandi @valentino-razza @gabrielenava

[CarlottaSartore]

Added new commit for contact switching in the velocity controller C.C. @gabrielenava

[gabrielenava]

merging!

cc @CarlottaSartore