Physics support

[lilleyse]

Generate static physics meshes for tiles similar to Cesium for Unreal/Unity. Then we should be able to support vehicle and character movement, raycast picking, camera collision, and more.

• Does this build on top of USD (e.g. USD physics schema) or Physics Core or even lower level (like PhysX directly).
• What happens if the georeference origin changes or we support automatic origin rebasing?
• We'll probably start by using the glTF mesh as the collision mesh, but longer term may want to pre-generate a simplified mesh and encode with MSFT_CollisionPrimitives or similar.

[lilleyse]

Requested on the forum: https://community.cesium.com/t/cesium-for-omniverse-workflow/32200/2

Mainly we're waiting for Fabric Scene Delegate to get physics support before we tackle this.

[und-miller]

We're excited for this