[costmap] add node to perform elevation mapping

[yambati03]

Description

This PR does the following:

• Rehaul the simulation to contain the field scan from ERC
• Separate bringup.launch.py into another script specifically for simulation
• Make a node to perform elevation mapping

Testing Steps (if relevant)

Test Case 1

1. Do this thing
2. Do that thing
3. Make the thing do the thing

Expectation: The thing which does the thing does the thing

Design Presentation (only required for major additions)

Post the link to your presentation here and be sure to update the presentation document if this PR results in a significant addition to the stack

Self Checklist

• [ ] I have formatted my code using ament_uncrustify --reformat
• [ ] I have tested that the new behavior works