Add Unicycle Trajectory Generator

[LoreMoretti]

This PR provides a Unicycle Trajectory Generator that combined with the Unicycle Trajectory Planner of #844 mimics the functionalities of the planner used in walking-controllers.

Considering a Master-Slave architecture, Unicycle Trajectory Generator acts as the master.

It is in charge of:

• advancing the Unicycle Trajectory Planner any time a new trajectory needs to be computed
• merging the current trajectory with the next one returned by the Unicycle Trajectory Planner
• unrolling the current trajectory (i.e., it advances it over time)

This PR should be merged after #844.

[LoreMoretti]

@traversaro the failed conda-forge dependencies CIs (for Ubuntu/Windows) seem some download error. Could you confirm?

[traversaro]

@traversaro the failed conda-forge dependencies CIs (for Ubuntu/Windows) seem some download error. Could you confirm?

Yes, it is due to https://github.com/conda/infrastructure/issues/906 as we are using packages from robostack-staging in the CI. I wonder if this could be mitigated using conda instead of mamba, I will try.