added Nav2 path planning

[jruths]

Main contribution is adding a Nav2-based path planner. This is through the planning/nav2_path_planner_node. Part of the Nav2 stack must be launched to support this, and these new launch files are in launches/launch.nav2.py

Other changes included:

• Dockerfile needed to install Nav2
• Substantial edits to grid_summation_node
• Added a separate route costmap publisher, which also publishes the goal point for the path generation
  • The logic for the route costmap needs to be revisited... it does some funky things towards the end of the route
• Added visualization of the Nav2 edits in the default rviz file
• Added a few launch options for easier debugging (specifically for map manager and for rviz)

[jruths]

Noting the conflict in launch.vehicle.py. I think I just added stuff in there and commented out rtp. So I think you can just take my version.