Add newton-usd-schemas alongside MJC equivalents

[andrewkaufman]

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

New Feature

Feature Description

newton-usd-schemas provide some redudant settings to MJC equivelents, which work for more Newton solvers. Over time we expect the MJC attributes to be deprecated in favor of the newton ones.

We should author both for now, until mujoco starts to incorporate the newton schemas directly.

Additional context or alternatives

https://pypi.org/project/newton-usd-schemas/

Code of Conduct

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