[solver-constraint] Rename epsilon by energyWeight

[EulalieCoevoet]

When solving an inverse problem, we add a term in the optimization cost function that minimizes the actuation energy. This is achieved by regularizing the QP matrix Q through the addition of epsilon*Waa, where epsilon is selected to be sufficiently small to avoid disrupting the quality of the effector positioning.

Problem:
We named this parameter epsilon, which isn't clear to users.

In this PR:

• Rename epsilon to energyWeight in both the C++ code and user API
• Use the deprecation mechanism for the user API only
• Update the scenes

Also:

• Improve the description of the objective data, set it as read-only, and change its default value to 0
• Remove the deprecated rebuildSystem() method

Needs: SofaDefrost/SoftRobots#344

[hugtalbot]

I would advise to use a compatibility layer to avoid breaking scenes/tutorials that would not have been updated

As example is available in https://github.com/sofa-framework/sofa/pull/5518/changes (see the class CollisionModel)

[hugtalbot]

I would suggest to use an homogeneous way to manage the lifecycle in all codes :

    proximity.setOriginalData(&d_contactDistance);
    addAlias(&d_contactDistance, "proximity");

This would avoid the boiler plate code in the init ;)
Thanks ✌️

@bakpaul will test this PR soon with his new sofa-test-action !