Lap timing and finish line checking

[hzheng40]

Explore the option of using @ayoubraji 's method of finish line condition checking.
(Project agent's current position onto the centerline of the track and check the cumulated arc length)

Single finish line for all agents on the track.

[ayoubraji]

In this fork I completed the integration of the solution I proposed in #2 but I'm not able to test it properly because I'm facing an issue on f1tenth_gym_ros after I cleaned my docker from all the old images and built all again. The issue is the same described here.

[ayoubraji]

Pull request sent. Check the description for further details.
I hadn't time to work on it before and I've also been blocked by the issue that has just been solved. Sorry for the delay.