Add ergoCub head configuration

[mfussi66]

This PR adds the proper configuration of the neck and head of ergoCub. The face configuration files are consequently removed, and eyes_tilt joint becomes cam_tilt. Since there are no eyes, the number of joints in the head goes from 6 to 4.

Finally, position pid values are updated for:

• neck pitch
• neck roll
• camera tilt cc @pattacini @Nicogene