Sim launch position arg

[PatXue]

What type of PR is this? (check all applicable)

• [ ] Refactor
• [x] Feature
• [ ] Bug Fix
• [ ] Optimization
• [ ] Documentation Update

Description

Changed arguments in single and 2 buggy simulator launch files to allow user to start buggy(s) from any distance along the planned trajectory by passing in command line arguments.

QA Instructions, Screenshots, Recordings

Tested single buggy sim on both Gabe's and my computer, and appears to behave as expected. Tested double buggy sim on my computer, and also seems to work as expected.

[christianvluu]

I was imagining we have certain "keypoints/checkpoints" around the course where the buggies could start, instead of inputting a distance.

Perhaps there's a different option upon launching that could allow you to specify the start location down to the particular coordinate/distance along the path, but in general, we're only going to be starting the simulation at a few positions right? @Jackack

[Jackack]

The idea is to use distance to specify the key points

[christianvluu]

Yeah, was gonna ask what if we want to start slightly off from the path.

[Jackack]

I requested a change to add raw coordinates as well, if that's what auto testing wants. There's also already a dictionary of key points in engine.py. It's commented out by this commit but we should keep that feature too.

[PatXue]

Added back in ability to use start_pos argument as a dictionary key for starting_poses, will work later on inputting utm coords