Add simple notebook example for joint control

[giotherobot]

In this PR I add a very basic example that shows a basic way of directly controlling the robot joints using the python bindings of BLF.

The example should be self-contained (as much as possible, we are still using gazebo so a full online experience is not the goal).

Feel free to suggest modifications and clarifications!

[GiulioRomualdi]

That's cool! I would just rename the example folder in a way it is more related to the the example, like the others

[traversaro]

Not sure how to comment on line in notebook, but can we use conda in place of mamba ? Since conda switched to conda-libmamba-solver solver it should be almost as fast as mamba, and it is actively mantained while mamba has some corner case issues. Ideally in the long term I would like to sticks docs to use conda for environment-related workflows and pixi for project-related (and locked) workflows, without using mamba and micromamba to reduce confusion in users (see robotology/robotology-superbuild#1653 for the rationale).