Make SDF boundary value configurable

[rmurai0610]

Motivation and Context

Made the boundary value of sdf configurable. The default was 0 (i.e. solid wall around the map) but this does not make sense in MPC setting, where we may want to encourage the motion planner to explore outside the current local map.

How Has This Been Tested

It's not tested yet

Types of changes

• [ ] Docs change / refactoring / dependency upgrade
• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• [x] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [x] I have completed my CLA (see CONTRIBUTING)
• [ ] I have added tests to cover my changes.
• [x] All new and existing tests passed.