[#303] using lgsvl vehicle_odometry directly in lgsvl_interface

Description

Closes #303 (closed)

Notes for Reviewer

• I thought /lgsvl/vehicle_odometry might replace the other lgsvl/gnss_odom, but it would not as the pose only comes from gnss_odom. To reduce ambiguity, I renamed all nav_msgs related odometry to nav_odom, and used veh_odom for vehicle_odometry whenever possible.
• Still using param for topic names, did not refactor that part, better to do that is a separate issue.
• The output odometry topic from lgsvl_interface as /odometry is redundant to /lgsvl/vehicle_odometry. I thought of disabling that output and directly remap /lgsvl/vehicle_odometry to that and only consume the value and not republish. The design in vehicle_interface dictates publishing of vehicle_odometry as a minimum requirement, so did not remove that.

Checklist

• Documentation was updated

/milestone %After AVP