Convert links and joints to USD

[andrewkaufman]

Is this a new feature, an improvement, or a change to existing functionality?

New Feature

Feature Description

This task covers all data conversion for link, intertial, visual, collision, geometry, and joint but does not include materials (even on the visuals)

We should start by only supporting STL meshes, so we can achieve MVP for a working robot.

Ignore any GAP concepts (eg mimic joints) for now & document them on #17 so we remember to add warnings later on.

Additional context or alternatives

No response

Code of Conduct

• I agree to follow urdf-usd-converter Code of Conduct
• I have searched the open issues and have found no duplicates

[andrewkaufman]

@ft-lab let me know if you'd prefer to break this down into sub issues. I didn't feel the need, but it is definitely more than I attempted in my first mujoco MR... There I only had visuals & not the physics properties.