This change introduces two new USD API schema:
* MjcEqualityAPI - base API for representing MuJoCo equality constraints in USD, this will typically be applied to joints such as UsdPhysicsFixedJoint.
* MjcEqualityWeldAPI - extends MjcEqualityAPI for MuJoCo's weld equality constraints with an attribute for torqueScale.
The usd_decoder is updated to parse UsdPhysicsFixedJoints and convert the new schema attributes into the appropriate mjsEquality data fields.
PiperOrigin-RevId: 856723634
Change-Id: I0982fd3168b643f8e91d87bb5ae5933e526b63a1
Add usd_decoder to mujoco/plugin.
- Previously was src/experimental/usd/usd_to_mjspec.cc, now that same spec is returned by the plugin.
PiperOrigin-RevId: 854350962
Change-Id: Ia980190a557c50ce8197980922a2594b613859b4
Sam Haves