[bugfix] - compute navmesh visualization node AABB

[aclegg3]

Motivation and Context

Set the SceneNode bounding box for navmesh visualization nodes upon creation. Fixes incorrect culling on navmesh visualization causing navmesh wireframes to disappear for some camera positions.

How Has This Been Tested

locally in viewer

Types of changes

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

Checklist

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