Add OMI_collider and OMI_physics_body extension validation

[aaronfranke]

EDIT: This is incomplete, do not merge.

This PR adds validation for the OMI_collider and OMI_physics_body glTF extensions. This could be expanded further later, but the code that exists so far should be fully working (it successfully validates several test files).

OMI's specs can be found here https://github.com/omigroup/gltf-extensions/tree/main/extensions/2.0

The Khronos glTF repo pull request can be found here: https://github.com/KhronosGroup/glTF/pull/2258