refactor: nested launch files

[akevinge]

Addresses #388

Changes

• Moves all launch files to launches directory
• Nests perception launch description in launches/vehicle.launch.py
• launches/carla.launch.py returns a copy of vehicle launch description (identical atm)
• Adds navigator CLI. Launches can now be run with navigator launch {perception, vehicle, carla}

This PR is meant to serve as a foundation for building more complex launch GUI's (among other things) in the future.

[danielv012]

Tested on the quad and it works great. Lots of error catching and documentation is also a big plus. Having a set of "navigator" commands, especially for launching, will be a big help not only for devs on the team but aslo for other users. This is my main concern and/or possible adjustment (that I can think of as of right now):

• While it's nice to abstract different subsystems into nested launch files, e.g. (launch.perception.py), it might not be viable to have nested launch files for specific subsystems. The majority of our testing will require at least some core functionality from each subsystem (top-down). So, I question if a localization-only subsystem, which needs the perception subsystem for example, will ever be used. Perhaps we could work towards a GUI where the user could select configurations instead of specific subsystems?

But we could use this nested organization to achieve that. The big question right now is what nodes will go where.

[akevinge]

The majority of our testing will require at least some core functionality from each subsystem (top-down). So, I question if a localization-only subsystem, which needs the perception subsystem for example, will ever be used.

I was wondering this too. I just assumed it was common to use bags to replace nodes a system depended on. By selecting configurations, do you mean a way to switch parameters? Or maybe a way to compose nodes across subsystems?

The big question right now is what nodes will go where.

Assuming you mean the latter, if you could provide an example where this would be needed that would help.

P.S. will have faster response times now that I'm back in Dallas.

[akevinge]

Build is failing due to error in workflow file. Please merge #406 for checks to pass.