🚧 Implement pybind11 bindings for the KinDynComputations object

[GiulioRomualdi]

The PR is still in draft since I've to implement the bindings for the twist and I've to add the tests

This is an example of usage

import idyntree.pybind as iDynTree

kindyn = iDynTree.KinDynComputations()
kindyn.model = iDynTree.get_random_model(10)
kindyn.set_robot_state([0] * kindyn.get_nr_of_degrees_of_freedom(),
                       [0] * kindyn.get_nr_of_degrees_of_freedom(),
                       [0,0,-9.81])

mass_matrix = kindyn.get_free_floating_mass_matrix()
print(mass_matrix)

this is the output

array([[  25.57634706,    0.        ,    0.        ,    0.        ,
         -15.9249302 ,  -54.83262385,   -8.8700384 ,    4.9886203 ,
           4.58045113],
       [   0.        ,   25.57634706,    0.        ,   15.9249302 ,
           0.        ,   17.75681755,   12.90257969,   -8.81148874,
           0.98227791],
       [   0.        ,    0.        ,   25.57634706,   54.83262385,
         -17.75681755,    0.        ,  -29.49926001,   -2.30219837,
           3.81275983],
       [   0.        ,   15.9249302 ,   54.83262385,  319.99566805,
         -83.66501237, -109.7314934 ,  -97.47332486,   25.4046302 ,
          -2.72756328],
       [ -15.9249302 ,    0.        ,  -17.75681755,  -83.66501237,
         322.25186762,   50.53625654,   99.22406621,    5.48370803,
          -3.07273261],
       [ -54.83262385,   17.75681755,    0.        , -109.7314934 ,
          50.53625654,  405.52787367,   76.84201426,  -65.68563465,
           2.72448946],
       [  -8.8700384 ,   12.90257969,  -29.49926001,  -97.47332486,
          99.22406621,   76.84201426,  103.53784748,  -33.24504489,
           0.        ],
       [   4.9886203 ,   -8.81148874,   -2.30219837,   25.4046302 ,
           5.48370803,  -65.68563465,  -33.24504489,   27.92202853,
           0.        ],
       [   4.58045113,    0.98227791,    3.81275983,   -2.72756328,
          -3.07273261,    2.72448946,    0.        ,    0.        ,
           6.64783251]])

[traversaro]

Removing myself from the reviewers, feel free to add me back if the PR is being worked on.

[GiulioRomualdi]

We can close since https://github.com/robotology/idyntree/pull/1001 implements the same feature