Fix Robot Model in Gazebo and RViz2

[wltjr]

Three issues:

• [x] Direction robot moves or is facing or side bucket ladder is on
• [x] Sprocket miss-alignment in Gazebo but not Rviz2
• [x] Robot exploding on start and coming back together in Gazebo
• [x] Robot rolling by default in Gazebo, should be stationary

This is mostly an issue in Gazebo and not RViz2, although, the issue of moving backward might exist in both. Either the robot is moving backward, or the bucket ladder is on the wrong end, so the model is backwards.

There is also the issue of the sprockets being misaligned and floating in Gazebo, despite being properly aligned in RViz2.

Finally, there is some possible physics issue with the robot when it initially moves, could be due to being stuck in the floor on start. It also should not be rolling.

[wltjr]

Sprocket issue seems to have resolved itself.

[wltjr]

Robot exploding was due to being in the floor, the chassis was raised up, and other links were made to use that as the parent instead of base_link, refer to commit that closed the issue.