Add zmp generator and populate all outputs of the unycycle trajectory generator

[LoreMoretti]

Some of the outputs of the UnicycleTrajectoryGenerator were not being populated.

This PR fixes it.

Moreover, the ZMP generator (and its outputs) is added to the UnicycleTrajectoryGenerator

[S-Dafarra]

At the code level, it looks good. What I am a bit afraid of is that from outside it is not clear that the different trajectories are not coherent with each other. At the unicycle planner level, you are calling to different generators, so somehow you can expect them to be separate. Here instead, the output is in a single data structure. Maybe it would be useful to have a trigger to turn on or off this output?

[LoreMoretti]

At the code level, it looks good. What I am a bit afraid of is that from outside it is not clear that the different trajectories are not coherent with each other. At the unicycle planner level, you are calling to different generators, so somehow you can expect them to be separate. Here instead, the output is in a single data structure. Maybe it would be useful to have a trigger to turn on or off this output?

You're right! It makes totally sense.

With the commit ecbd51f I tried to make the dcmTrajectory and the zmpTrajectory optional (and enabled by boolean flags).

I like the fact that std::optional makes the code cleaner in my opinion.

There's the drawback. This change makes the blf Unicycle Trajectory Generator not backward compatible. But I think the number of users is still low.

Let me know what you think.

[S-Dafarra]

There's the drawback. This change makes the blf Unicycle Trajectory Generator not backward compatible. But I think the number of users is still low.

Let me know what you think.

It should be fine by changing the version number. On the other hand, another alternative is to apply this change only for the data you added