Add Noise to Slotcar Plugin

[arjo129]

New feature implementation

Implemented feature

This should help simulate real world scenarios where robots might report noisy location.

To use publish a gz.sim.SensorNoise message to /slotcar/translation_noise.

Note: This feature only works on GZ-SIM

[arjo129]

No Idea why I need this here but oh-well. I guess I can move the sdf code into the header and then not need it?

[luca-della-vedova]

Going forward my preference would be to just stick to gz plugins and avoid the additional layer of complexity added by moving the logic to a common class, after all there won't be a gz_classic implementation soon anyway.

[arjo129]

Makes sense. For immediate term though I need to update slotcar common cause most of the logic is there.

[luca-della-vedova]

I had a typed review but it's gone :|

From the top of my head:

• There seems to be a callback / subscription for the translation_noise but none for the rotation_noise, can we have one of that as well? Otherwise it seems it might be impossible to set.
• Can we have also some basic docs in the plugin's README to show how to use this feature, i.e. what CLI command can be used to set the translation and rotation noise?
• After looking at the code closer I agree that keeping the split is a bit easier now, with the refactor done hopefully we can get rid of the rmf_robot_sim_common package "soon".

The rest looks alright (if I can test it!), there are many ways to approach this (parameter in SDF or set through a service, service that sets for all the models vs one per robot) but they all have their pros and cons and don't really have feelings strong enough to advocate for a different way to do it.