Fix the colors for iCubV2_5 and iCubV3

[GiulioRomualdi]

This PR closes #216 and required robotology/simmechanics-to-urdf#51 to properly work

In detail, this PR defines the colors for each link of the robots. I've chosen the color arbitrally let me know if you prefer a different palette.

After this PR and robotology/idyntree#961 if iCub is loaded in the iDynTree visualizer we will get:

TODO

• Once Add the possibility to assign the colors in the yaml file when the urdf model is generated simmechanics-to-urdf#51 has been merged update the CI Not required since the ci already get the latest commit of simmechanics-to-urdf

cc @robotology/iit-artificial-mechanical-intelligence @Nicogene

[traversaro]

The color for iCubV2_5 seems suspisciously iCubGenova04 specific. :D
However, for me the one that does the job decide which color to pick, so I do not see a big problem with this color. Just pinging @pattacini and @Nicogene for a double check.

[pattacini]

Just pinging @pattacini for a double check.

Fine with me too 👍🏻
(although I personally dislike the iCub in red 😄 why did you choose it for iCubGenova04!)

[traversaro]

Note that all the link of the model will remain "gray" when displayed in Classic Gazebo due to gazebosim/sdformat#526 (comment) .

[traversaro]

robotology/simmechanics-to-urdf#51 was merged!

[GiulioRomualdi]

Since the CI already uses the latest commit of simmechanics-to-urdf we can avoid to update the workflow