Merge example/ilqr_bimanual_manipulability into master

Hi Boyang,

Thanks for your contribution on RCFS, before definitely adding your example on the master branch there are some small things to fix:

1. Fix the header of your example, especially the description of your example 😄
2. Use an object to store your example's parameters (see: https://gitlab.idiap.ch/rli/robotics-codes-from-scratch/-/blob/master/python/iLQR_manipulator.py#L88 )

Thanks!

Have a nice day, Jérémy